NCSA--A Beginner`s Guide to HTML
Contents
1. A Beginner s Guide to HTML Primer intrd ull length version Printable versio Pardi Part Ji Pardi PDF versio This is a primer for producing documents in HTML the hypertext markup language used on the World Wide Web This guide is intended to be an introduction to using HTML and creating files for the Web Links are provided to additional information You should also check your local bookstore there are many volumes about the Web and HTML that could be useful etting Started m Terms to Kno m What Isn t Covered m HTML Version TML Document hat an HTML Document TML Editor etting Your Files on a Serve ags Explained he Minimal HTML Document D Y Q te ey Q arkup Tags E 4 a UJ D qm eH ximo fe 5S a reformatted Text Extended Quotation Forced Line Breaks Postal Addresse orizontal Rule haracter Formatting n Logical Versus Physical Siyieg m Escape Sequences Linking a Relative Pathnames Versus Absolute Pathnames URLS m Links fo Specific Sectiong a Maio mage Size Attribute igning Image ternate Text for Image mages as Hyperlink Background Graphic Background Colo xternal Images Sounds and Animation EHREHEEHESs i m Table Tag m General Table Format m Tables for Nontabular Information roubleshooting a mbed Only Anchors and Character Tag o the Final Step ommenting Your File or More Information Style Guide ther Introductory Document Addit2. ALT HOTLIST ALIGN MIDDLE gt Again only one line of text is centered the rest is below the image Images without Text To display an image without any associated text e g your organization s logo make it a separate para graph Use the paragraph ALIGN attribute to center the image or adjust it to the right side of the window as shown below lt p ALIGN CENTER gt lt IMG SRC hotlist gif ALT HOTLIST gt lt p gt which results in The image is centered this paragraph starts below it and left justified Alternate Text for Images Some World Wide Web browsers primarily the text only browsers such as Lyng cannot display images Some users turn off image loading even if their software can display images especially if they are using a modem or have a slow connection HTML provides a mechanism to tell readers what they are missing on your pages if they can t load images The ALT attribute lets you specify text to be displayed instead of an image For example lt IMG SRC UpArrow gif ALT Up gt where UpArrow gif is the picture of an upward pointing arrow With graphics capable viewers that have image loading turned on you see the up arrow graphic With a text only browser or if image loading is turned off the word Up is shown in your window in place of the image You should try to include alternate text for each image you use in your document which is a courtesy for your readers or for users
3. amount of whitespace including spaces linefeeds and carriage returns are automatically compressed into a single space when your HTML document is displayed in a browser So you don t have to worry about how long your lines of text are Word wrapping can occur at any point in your source file without affecting how the page will be displayed In the bare bones example shown in the Minimal HTML Document section the first paragraph is coded as lt P gt Welcome to the world of HTML This is the first paragraph While short it is still a paragraph lt P gt In the source file there is a line break between the sentences A Web browser ignores this line break and starts a new paragraph only when it encounters another lt P gt tag Important You must indicate paragraphs with lt P gt elements A browser ignores any indentations or blank lines in the source text Without lt P gt elements the document becomes one large paragraph One exception is text tagged as preformatted which is explained below For example the following would produce identical output as the first bare bones HTML example lt Hi gt Level one heading lt H1 gt lt P gt Welcome to the world of HTML This is the first paragraph While short it is still a paragraph lt P gt lt P gt And this is the second paragraph lt P gt To preserve readability in HTML files put headings on separate lines use a blank line or two where it helps identify the start of
4. however Comments such as the name of the person updating a file the software and version used in creating a file or the date that a minor edit was made are the norm To include a comment enter lt your comments here gt You must include the exclamation mark and the hyphens as shown 25 For More Information This guide is only an introduction to HTML not a comprehensive reference Below are additional online sources of information Remember to check a bookstore near you for Web and HTML books Style Guides The following offer advice on how to write good HTML m Composing Good HTM m WS3C s style guide for online hypertext Other Introductory Documents These cover similar information as this guide ntroduction to HTM he Yale Center for Advanced Instructional Media he HTML Quick Reference Guide TML CSS Tutoria pages which provides a comprehensive listing of HTML codes HEHE E s Additional Online References A description of SGML the Standard Generalized Markup Language snazzy stuff that is really perking up the Web Thanks NCSA acknowledges and thanks the many Web users who have commented on this guide Thanks also to the NCSA reviewers and contributors as well as the author of the first version of this guide Contact mailto webmaster ncsa uiuc edu subject General Internet WWW HTMLPrimerAll htm with questions regarding this page All righ
5. a new section and separate paragraphs with blank lines in addition to the lt P gt tags These extra spaces will help you when you edit your files but your browser will ignore the extra spaces because it has its own set of rules on spacing that do not depend on the spaces you put in your source file NOTE The lt P gt closing tag may be omitted This is because browsers understand that when they encounter a lt P gt tag it means that the previous paragraph has ended However since HTML now allows certain attributes to be assigned to the lt P gt tag it s generally a good idea to include it Using the lt P gt and lt P gt as a paragraph container means that you can center a paragraph by including the ALIGN alignment attribute in your source file lt P ALIGN CENTER gt This is a centered paragraph See the formatted version below lt P gt This is a centered paragraph It is also possible to align a paragraph to the right instead by including the ALIGN RIGHT attribute ALIGN LEFT is the default alignment if no ALIGN attribute is included the paragraph will be left aligned TH A Beginners Guide E to HTML Lists HTML supports unnumbered numbered and definition lists You can nest lists too but use this feature sparingly because too many nested items can get difficult to follow Unnumbered Lists To make an unnumbered bulleted list 1 start with an opening list lt UL gt for unnumbered list
6. in italics rm filename deletes the file Physical Styles lt B gt bold text lt I gt italic text lt TT gt typewriter text e g fixed width font Escape Sequences a k a Character Entities Character entities have two functions m escaping special characters m displaying other characters not available in the plain ASCII character set primarily characters with diacritical marks Three ASCII characters the left angle bracket lt the right angle bracket gt and the ampersand amp have special meanings in HTML and therefore cannot be used as is in text The angle brackets are used to indicate the beginning and end of HTML tags and the ampersand is used to indicate the beginning of an escape sequence Double quote marks may be used as is but a character entity may also be used To use one of the three characters in an HTML document you must enter its escape sequence instead amp lt the escape sequence for lt amp gt the escape sequence for gt amp amp the escape sequence for amp Additional escape sequences support accented characters such as amp ouml a lowercase o with an umlaut 6 amp ntilde a lowercase n with a tilde amp Egrave an uppercase E with a grave accent E You can substitute other letters for the o n and E shown above Visit the World Wide Web Consortium for a complete list of pecial characters NOTE Unlike the rest of HTML the escape sequences are case sensitive You
7. lt DL gt TH A Beginners Guide to HTML i The output looks like NCSA NCSA the National Center for Supercomputing Applications is located on the campus of the Universi ty of Illinois at Urbana Champaign Cornell Theory Center CTC is located on the campus of Cornell University in Ithaca New York The lt DT gt and lt DD gt entries can contain multiple paragraphs indicated by lt P gt paragraph tags lists or other definition information The COMPACT attribute can be used routinely in case your definition terms are very short If for example you are showing some computer options the options may fit on the same line as the start of the definition lt DL COMPACT gt lt DT gt i lt DD gt invokes NCSA Mosaic for Microsoft Windows using the initialization file defined in the path lt DT gt k lt DD gt invokes NCSA Mosaic for Microsoft Windows in kiosk mode lt DL gt The output looks like i invokes NCSA Mosaic for Microsoft Windows using the initialization file defined in the path kinvokes NCSA Mosaic for Microsoft Windows in kiosk mode Nested Lists Lists can be nested You can also have a number of paragraphs each containing a nested list in a single list item Here is a sample nested list lt UL gt lt LI gt A few New England states lt UL gt lt LI gt Vermont lt LI gt New Hampshire lt LI gt Maine lt UL gt lt LI gt Two Midwestern states lt UL gt lt LI g
8. not additive For example you might expect that lt B gt lt I gt some text lt I gt lt B gt would produce bold italic text On some browsers it does other browsers interpret only the innermost tag 24 TH P NCSA A Beginners Guide to HTML Do the Final Steps Validate Your Code When you put a document on a Web server be sure to check the formatting and each link including named anchors Ideally you will have someone else read through and comment on your file s before you consider a document finished You can run your coded files through one of several on line HTML validation services that will tell you if your code conforms to accepted HTML If you are not sure your coding conforms to HTML specifications this can be a useful teaching tool Fortunately the service lets you select the level of conformance you want for your files i e strict level 2 level 3 If you want to use some codes that are not officially part of the HTML specifications this latitude is helpful Dummy Images When an lt IMG SRC gt tag points to an image that does not exist a dummy image is substituted by your browser software When this happens during your final review of your files make sure that the referenced image does in fact exist that the hyperlink has the correct information in the URL and that the file per mission is set appropriately world readable Then check online again Update Your Files If the contents of a fil
9. or vi on UNIX machines SimpleText on a Macintosh Notepad on a Windows machine You can also use word processing software if you remember to save your document as text only with line breaks HTML Editors Some WYSIWYG editors are also available e g Claris Home Page or Adobe PageMill both for Windows and Macintosh You may wish to try one of them after you learn some of the basics of HTML tagging WYSIWYG is an acronym for what you see is what you get it means that you design your HTML document visually as if you were using a word processor instead of writing the markup tags in a plain text file and imagining what the resulting page will look like It is useful to know enough HTML to code a document before you determine the usefulness of a WYSIWYG editor in case you want to add HTML features that your editor doesn t support If you haven t already selected your software refer to Tom Magliery s jonline listing of HTML editors organized by platform to help you in your search for appropriate software Getting Your Files on a Server If you have access to a Web server at school or work contact your webmaster the individual who main tains the server to see how you can get your files on the Web If you do not have access to a server at work or school check to see if your community operates a FreeNet a community based network that provides free access to the Internet Lacking a FreeNet you may need to contact a local Internet prov
10. tag 2 enter the lt LI gt list item tag followed by the individual item no closing lt LI gt tag is needed 3 end the entire list with a closing list lt UL gt tag Below is a sample three item list lt UL gt lt LI gt apples lt LI gt bananas lt LI gt grapefruit lt UL gt The output is apples m bananas m grapefruit The lt LI gt items can contain multiple paragraphs Indicate the paragraphs with the lt P gt paragraph tags Numbered Lists A numbered list also called an ordered list from which the tag name derives is identical to an unnum bered list except it uses lt OL gt instead of lt UL gt The items are tagged using the same lt LI gt tag The follow ing HTML code lt OL gt lt LI gt oranges lt LI gt peaches lt LI gt grapes lt OL gt produces this formatted output 1 oranges 2 peaches 3 grapes Definition Lists A definition list coded as lt DL gt usually consists of alternating a definition term coded as lt DT gt and a definition definition coded as lt DD gt Web browsers generally format the definition on a new line and indent it The following is an example of a definition list lt DL gt lt DT gt NCSA lt DD gt NCSA the National Center for Supercomputing Applications is located on the campus of the University of Illinois at Urbana Champaign lt DT gt Cornell Theory Center lt DD gt CTC is located on the campus of Cornell University in Ithaca New York
11. BGCOLOR white text TEXT and silvery hyperlinks LINK The six digit number and letter combinations represent colors by giving their RGB red green blue value The six digits are actually three two digit numbers in sequence representing the amount of red green or blue as a hexadecimal value in the range 00 FF For example 000000 is black no color at all FF0000 is bright red OOOOFF is bright blue and FFFFFF is white fully saturated with all three colors These number and letter combinations are generally rather cryptic Fortunately an online resource is available to help you track down the combinations that map to specific colors and there is software available for you to do this on your workstation n For some basic colors typically those in the standard sixteen color Windows 3 1 palette you can also use the name of the color instead of the corresponding RGB value For example black red blue and cyan are all valid for use in place of RGB values However while not all browsers will understand all color names any browser that can display colors will understand RGB values so use them whenever possible TH A Beginners Guide E to HTML External Images Sounds and Animations You may want to have an image open as a separate document when a user activates a link on either a word or a smaller inline version of the image included in your document This is called an external image and it is useful if yo
12. ar if the image is viewed by itself without an enclosing HTML document For example to include a self portrait image in a file along with the portrait s dimensions enter lt IMG SRC SelfPortrait gif HEIGHT 100 WIDTH 65 gt NOTE Some browsers use the HEIGHT and WIDTH attributes to stretch or shrink an image to fit into the allotted space when the image does not exactly match the attribute numbers Not all browser developers think stretching shrinking is a good idea so don t plan on your readers having access to this feature Check your dimensions and use the correct ones Aligning Images You have some flexibility when displaying images You can have images separated from text and aligned to the left or right or centered Or you can have an image aligned with text here lt IMG SRC hotlist gif ALT HOTLIST ALIGN RIGHT gt Try several possibilities to see how your information looks best Aligning Text with an Image By default the bottom of an image is aligned with the following text as shown in this paragraph You can align images to the top or center of a paragraph using the ALIGN attributes TOP and MIDDLE This text is aligned with the top of the image lt IMG SRC hotlist gif ALT HOTLIST ALIGN TOP gt Notice how the browser aligns only one line and then jumps to the bottom of the image for the rest of the text And this text is centered on the image lt IMG SRC hotlist gif
13. ased service The portnumber can generally be omitted That means unless someone tells you otherwise leave it out For example to include a link to this primer in your document enter lt A HREF http www ncsa uiuc edu General Internet WWW HTMLPrimer html gt NCSA s Beginner s Guide to HTML lt A gt This entry makes the text NCSA s Beginner s Guide to HTML a hyperlink to this document There is also a mailto scheme used to hyperlink email addresses but this scheme is unique in that it uses only a colon instead of between the scheme and the address You can read more about mailto For more information on URLs refer to a WWW Names and Addresses URIs URLs URNg m IA Beginner s Guide to URLg Links to Specific Sections Anchors can also be used to move a reader to a particular section in a document either the same or a different document rather than to the top which is the default This type of an anchor is commonly called a named anchor because to create the links you insert HTML names within the document This guide is a good example of using named anchors in one document The guide is constructed as one document to make printing easier But as one long document it can be time consuming to move through when all you really want to know about is one bit of information about HTML Internal hyperlinks are used to create a table of contents at the top of this document These hyperlinks move you from one location in the docum
14. because links can be included in table cells some authors use a table with no borders to create one image from separate im ages Browsers that can display tables properly show the various images seamlessly making the created image seem like an image map one image with hyperlinked quadrants Using table borders with images can create an impressive display as well Experiment and see what you like 22 TH A inners Guide a to HTML i Fill out Forms Web forms let a reader return information to a Web server for some action For example suppose you collect names and email addresses so you can email some information to people who request it For each person who enters his or her name and address you need some information to be sent and the respondent s particulars added to a data base This processing of incoming data is usually handled by a script or program written in Perl or another language that manipulates text files and information If you cannot write a program or script for your incoming information you need to find someone who can do this for you The forms themselves are not hard to code They follow the same constructs as other HTML tags What could be difficult is the program or script that takes the information submitted in a form and processes it Because of the need for specialized scripts to handle the incoming form information are not discussed in this primer Check the Additional Online Reference section for mor
15. cannot for instance use amp LT instead of amp 1t TH b NCBA inners Guide A to HTM Linking The chief power of HTML comes from its ability to link text and or an image to another document or section of a document A browser highlights the identified text or image with color and or underlines to indicate that it is a hypertext link often shortened to hyperlink or just link HTML s single hypertext related tag is lt A gt which stands for anchor To include an anchor in your document 1 start the anchor with lt A include a space after the A 2 specify the document you re linking to by entering the parameter HREF filename followed by a closing right angle bracket gt 3 enter the text that will serve as the hypertext link in the current document 4 enter the ending anchor tag lt A gt no space is needed before the end anchor tag Here is a sample hypertext reference in a file called US html lt A HREF MaineStats html gt Maine lt A gt This entry makes the word Maine the hyperlink to the document MaineStats html which is in the same directory as the first document Relative Pathnames Versus Absolute Pathnames You can link to documents in other directories by specifying the relative path from the current docu ment to the linked document For example a link to a file NYStats html located in the subdirectory AtlanticStates would be lt A HREF AtlanticStates NYStats html gt New York lt A
16. e are static such as a biography of George Washington no updating is probably needed But for documents that are time sensitive or covering a field that changes frequently remember to update your documents Updating is particularly important when the file contains information such as a weekly schedule or a deadline for a program funding announcement Remove out of date files or note why something that appears dated is still on a server e g the program requirements will remain the same for the next cycle so the file is still available as an interim reference Browsers Differ Web browsers display HTML elements differently Remember that not all codes used in HTML files are interpreted by all browsers Any code a browser does not understand is usually ignored though You could spend a lot of time making your file look perfect using your current browser If you check that file using another browser it will likely display a little or a lot differently Hence these words of advice code your files using correct HTML Leave the interpreting to the browsers and hope for the best Commenting Your Files You might want to include comments in your HTML files Comments in HTML are like comments in a computer program the text you enter is not used by the browser in any formatting and is not directly viewable by the reader just as computer program comments are not used and are not viewable The comments are accessible if a reader views the source file
17. e information 23 TH NICE A inners Guide vii to HTML Troubleshooting Avoid Overlapping Tags Consider this example of HTML lt B gt This is an example of lt I gt overlapping lt B gt HTML tags lt I gt The word overlapping is contained within both the lt B gt and lt I gt tags A browser might be confused by this coding and might not display it the way you intend The only way to know is to check each popular browser which is time consuming and impractical In general avoid overlapping tags Look at your tags and try pairing them up Tags with the obvious exceptions of elements whose end tags may be omitted such as paragraphs should be paired without an intervening tag in between Look again at the example above You cannot pair the bold tags without another tag in the middle the first definition tag Try matching your coding up like this to see if you have any problem areas that should be fixed before you release your files to a server Embed Only Anchors and Character Tags HTML protocol allows you to embed links within other HTML tags lt H1 gt lt A HREF Destination html gt My heading lt A gt lt H1 gt Do not embed HTML tags within an anchor lt A HREF Destination html gt lt H1 gt My heading lt H1 gt lt A gt Although most browsers currently handle this second example the official HTML specifications do not support this construct and your file will probably not work with future browsers Reme
18. eilly and Associates Inc If you were in the NYStats html file and were referring to the original document US htm1 your link would look like this lt A HREF US html gt United States lt A gt In general you should use relative links whenever possible because 1 it s easier to move a group of documents to another location because the relative path names will still be valid 2 it s more efficient connecting to the server 3 there is less to type However use absolute pathnames when linking to documents that are not directly related For example consider a group of documents that comprise a user manual Links within this group should be relative links Links to other documents perhaps a reference to related software should use absolute pathnames instead This way if you move the user manual to a different directory none of the links would have to be updated URLs The World Wide Web uses Uniform Resource Locators URLs to specify the location of files on other servers A URL includes the type of resource being accessed e g Web gopher FTP the address of the server and the location of the file The syntax is scheme host domain port path filename where scheme is one of file a file on your local system ftp a file on an anonymous FTP server http a file on a World Wide Web server gopher a file on a Gopher server WAIS a file on a WAIS server news a Usenet newsgroup telnet a connection to a Telnet b
19. ent to another location in the same document Go to the of this document and then click on the Links to Specific Sections hyperlink in the table of contents You will wind up back here You can also link to a specific section in another document That information is presented first because understanding that helps you understand linking within one document TH i A Beginners Guide to HTML i Links Between Sections of Different Documents Suppose you want to set a link from document A documentA html to a specific section in another document MaineStats html Enter the HTML coding for a link to a named anchor documentA html In addition to the many state parks Maine is also home to lt a href MaineStats html ANP gt Acadia National Park lt a gt Think of the characters after the hash mark as a tab within the MaineStats html file This tab tells your browser what should be displayed at the top of the window when the link is activated In other words the first line in your browser window should be the Acadia National Park heading Next create the named anchor in this example ANP in MaineStats html lt H2 gt lt A NAME ANP gt Acadia National Park lt a gt lt H2 gt With both of these elements in place you can bring a reader directly to the Acadia reference in MaineStats html NOTE You cannot make links to specific sections within a different document unless either you have write permission to the coded
20. esent their regular Web pages Check out the for an excellent example of using tables to control page layout Think of your tabular information in light of the coding explained below A table has heads where you explain what the columns rows include rows for information cells for each item In the following table the first column contains the header information each row explains an HTML table tag and each cell contains a paired tag or an explanation of the tag s function Table Elements Element Description Vv lt TABLE gt lt TABLE defines a table in HTML If the BORDER attribute is present your browser displays the table with a border lt CAPTION gt lt CAPTION gt defines the caption for the title of the table The default posi tion of the title is centered at the top of the table The attribu te ALIGN BOTTOM can be used to position the caption below the table NOTE Any kind of markup tag can be used in the caption lt TR gt lt TR gt specifies a table row within a table You may define default attributes for the entire row ALIGN LEFT CENTER RIGHT and or VALIGN TOP MIDDLE BOTTOM See Table Attributes at the end of this table for more information lt TH gt lt TH gt defines a table header cell By default the text in this cell is bold and centered Table header cells may contain other attributes to d
21. etermine the characteristics of the cell and or its contents See Table Attributes at the end of this table for more information lt TD gt lt TD gt defines a table data cell By default the text in this cell is aligned left and centered vertically Table data cells may con tain other attributes to determine the characteristics of the cell and or its contents See Table Attributes at the end of this table for more information Table Attributes NOTE Attributes defined within lt TH gt lt TH gt or lt TD gt lt TD gt cells override the default alignment set ina lt TR gt lt TR gt The WIDTH attribute is deprecated Attribute Description ALIGN LEFT CENTER RIGHT Horizontal alignment of a cell VALIGN TOP MIDDLE BOTTOM Vertical alignment of a cell COLSPAN n The number n of columns a cell spans ROWS PAN n The number n of rows a cell spans NOWRAP Turn off word wrapping within a cell 21 TH NCSA A inners Guide to HTML General Table Format The general format of a table looks like this lt TABLE gt lt start of table definition gt lt CAPTION gt caption contents lt CAPTION gt lt caption definition gt lt TR gt lt start of header row definition gt lt TH WIDTH 40 gt first header cell contents lt TH gt lt TH WIDTH 60 g
22. gt These are called relative links because you are specifying the path to the linked file relative to the location of the current file You can also use the absolute pathname the complete URL of the file but relative links are more efficient in accessing a server They also have the advantage of making your documents more portable for instance you can create several web pages in a single folder on your local computer using relative links to hyperlink one page to another and then upload the entire folder of web pages to your web server The pages on the server will then link to other pages on the server and the copies on your hard drive will still point to the other pages stored there It is important to point out that UNIX is a case sensitive operating system where filenames are con cerned while DOS and the MacOS are not For instance on a Macintosh DOCUMENT HTML Docu ment HTML and document html are all the same name If you make a relative hyperlink to DOCU MENT HTML and the file is actually named document html the link will still be valid But if you upload all your pages to a UNIX web server the link will no longer work Be sure to check your filenames before uploading Pathnames use the standard UNIX syntax The UNIX syntax for the parent directory the directory that contains the current directory is For more information consult a beginning UNIX reference text such as Learning the UNIX Operating System from O R
23. ider that will post your files on a server for a fee Check your local newspaper for advertisements or with your Chamber of Commerce for the names of companies Tags Explained An elementis a fundamental component of the structure of a text document Some examples of elements are heads tables paragraphs and lists Think of it this way you use HTML tags to mark the elements of a file for your browser Elements can contain plain text other elements or both To denote the various elements in an HTML document you use tags HTML tags consist of a left angle bracket lt a tag name and a right angle bracket gt Tags are usually paired e g lt H1 gt and lt H1 gt to start and end the tag instruction The end tag looks just like the start tag except a slash precedes the text within the brackets HTML tags are Some elements may include an attribute which is additional information that is included inside the start tag For example you can specify the alignment of images top middle or bottom by including the appropriate attribute with the image source HTML code Tags that have optional attributes are NOTE HTML is not case sensitive lt title gt is equivalent to lt TITLE gt or lt TiT1lE gt There are a few ex ceptions noted in Escape Sequences below Not all tags are supported by all World Wide Web browsers If a browser does not support a tag it will simply ignore it Any text placed between a pair of unknown
24. ional Online Reference hank OJ IT amp lt O ou Oo lt O 2 w pei 3 Q a Q TH A Beginners Guide to HTML Getting Started Terms to Know WWW World Wide Web Web World Wide Web SGML Standard Generalized Markup Language a standard for describing markup languages DTD Document Type Definition this is the formal specification of a markup language written using SGML HTML HyperText Markup Language HTML is an SGML DTD In practical terms HTML is a collection of platform independent styles indicated by markup tags that define the various components of a World Wide Web document HTML was invented by Tim Berners Lee while at CERN the European Laboratory for Particle Physics in Geneva What Isn t Covered This primer assumes that you m know how to use or some other Web browser m have a general understanding of how Web servers and client browsers work m have access to a Web server or that you want to produce HTML documents for personal use in local viewing mode HTML Version This guide reflects the most current specification HTML Version 4 0 plus some additional features that have been widely and consistently implemented in browsers Future versions and new features for HTML are under development TH A Beginners Guide to HTML HTML Documents What an HTML Document Is HTML documents are plain text also known as ASCII files that can be created using any text editor e g Emacs
25. l window for the INCSA Publications Group alias You of course will enter another mail address TH A Beginners Guide to HTML Inline Images Most Web browsers can display inline images that is images next to text that are in X Bitmap XBM GIF or JPEG format Other image formats are also being incorporated into Web browsers e g the Portable Network Graphic PNG format Each image takes additional time to download and slows down the initial display of a document Carefully select your images and the number of images in a document To include an inline image enter lt IMG SRC ImageName gt where ImageName is the URL of the image file The syntax for lt IMG SRC gt URLs is identical to that used in an anchor HREF If the image file is a GIF file then the filename part of mageName must end with gif Filenames of X Bitmap images must end with xbm JPEG image files must end with jpg or jpeg and Portable Network Graphic files must end with png Image Size Attributes You should include two other attributes on lt IMG gt tags to tell your browser the size of the images it is downloading with the text The HEIGHT and WIDTH attributes let your browser set aside the appropriate space in pixels for the images as it downloads the rest of the file You can get the pixel size from your image processing software such as Adobe Photoshop Some browsers will also display the dimensions of an image file in the title b
26. mber that browsers can be forgiving when displaying improperly coded files But that forgiveness may not last to the next version of the software When in doubt code your files according to the HTML specifications see below Character tags modify the appearance of the text within other elements lt UL gt lt LI gt lt B gt A bold list item lt B gt lt LI gt lt I gt An italic list item lt I gt lt UL gt Avoid embedding other types of HTML element tags For example you might be tempted to embed a heading within a list in order to make the font size larger lt UL gt lt LI gt lt H1 gt A large heading lt H1 gt lt LI gt lt H2 gt Something slightly smaller lt H2 gt lt UL gt Although some browsers handle this quite nicely formatting of such coding is unpredictable because it is undefined For compatibility with all browsers avoid these kinds of constructs The Netscape lt FONT gt tag which lets you specify how large individual characters will be displayed in your window is not currently part of the official HTML specifications What s the difference between embedding a lt B gt within a lt LI gt tag as opposed to embedding a lt H1 gt within a lt LI gt Within HTML the semantic meaning of lt H1 gt is that it s the main heading of a document and that it should be followed by the content of the document Therefore it doesn t make sense to find a lt H1 gt within a list Character formatting tags also are generally
27. n displayed on top of the image Background images can be a texture linen finished paper for example or an image of an object a logo possibly You create the background image as you do any image However you only have to create a small piece of the image Using a feature called tiling a browser takes the image and repeats it across and down to fill your browser window In sum you generate one image and the browser replicates it enough times to fill your window This action is automatic when you use the background tag shown below The tag to include a background image is included in the lt BODY gt statement as an attribute lt BODY BACKGROUND filename gif gt Background Color By default browsers display text in black on a gray background However you can change both elements if you want Some HTML authors select a background color and coordinate it with a change in the color of the text Always preview changes like this to make sure your pages are readable For example many people find red text on a black background difficult to read In general try to avoid using high contrast images or images that use the color of your text anywhere within the graphic You change the color of text links visited links and active links links that are currently being clicked on using further attributes of the lt BODY gt tag For example lt BODY BGCOLOR 000000 TEXT FFFFFF LINK 9690CC gt This creates a window with a black background
28. ns lt BR gt 605 East Springfield Avenue lt BR gt Champaign Illinois 61820 5518 lt BR gt the output is National Center for Supercomputing Applications 605 East Springfield Avenue Champaign Illinois 61820 5518 Horizontal Rules The lt HR gt tag produces a horizontal line the width of the browser window A horizontal rule is useful to sep arate major sections of your document You can vary a rule s size thickness and width the percentage of the window covered by the rule Experiment with the settings until you are satisfied with the presentation For example lt HR SIZE 4 WIDTH 50 gt displays as TH A NC Guid m inners Guide Beginners PPT Character Formatting HTML has two types of styles for individual words or sentences logical and physical Logical styles tag text according to its meaning while physical styles indicate the specific appearance of a section For example in the preceding sentence the words logical styles was tagged as emphasis The same effect formatting those words in italics could have been achieved via a different tag that tells your browser to put these words in italics Logical Versus Physical Styles If physical and logical styles produce the same result on the screen why are there both In the ideal SGML universe content is divorced from presentation Thus SGML tags a level one heading as a level one heading but does not specify that the level one heading should be for in
29. of style you use If you tag with physical styles do so throughout a document If you use logical styles stick with them within a document Keep in mind that future releases of HTML might not support certain logical styles which could mean that browsers will not display your logical style coding For example the lt DFN gt tag short for definition and typically displayed in italics is not widely supported and will be ignored if the reader s browser does not understand it Logical Styles lt DFN gt for a word being defined Typically displayed in italics NCSA Mosaic is a World Wide Web browser lt EM gt for emphasis Typically displayed in italics Consultants cannot reset your password unless you call the help line lt CITE gt for titles of books films etc Typically displayed in italics A Beginner s Guide to HTML lt CODE gt for computer code Displayed in a fixed width font The lt stdio h gt header file lt KBD gt for user keyboard entry Typically displayed in plain fixed width font Enter passwd to change your password TH NC A Beginners Guide to HTML i lt SAMP gt for a sequence of literal characters Displayed in a fixed width font Segmentation fault Core dumped lt STRONG gt for strong emphasis Typically displayed in bold NOTE Always check your links lt VAR gt for a variable where you will replace the variable with specific information Typically displayed
30. py of the file that your browser reads to generate the information in your current window select View Source or the equivalent from the browser menu Most browsers have a View menu under which this command is listed The file contents with all the HTML tags are displayed in a new window This is an excellent way to see how HTML is used and to learn tips and constructs Of course the HTML might not be technically correct Once you become familiar with HTML and check the many online and hard copy references on the subject you will learn to distinguish between good and bad HTML Remember that you can save a source file with the HTML codes and use it as a template for one of your Web pages or modify the format to suit your purposes TH NCSA 4 A inners Guide ed to HTML Markup Tags HTML This element tells your browser that the file contains HTML coded information The file extension htm1 also indicates this an HTML document and must be used If you are restricted to 8 3 filenames e g LeeHome htm use only htm for your extension HEAD The head element identifies the first part of your HTML coded document that contains the title The title is shown as part of your browser s window see below TITLE The title element contains your document title and identifies its content in a global context The title is typically displayed in the title bar at the top of the browser window but not inside the window itself The
31. source of that document or that document already contains in document named anchors For example you could include named anchors to this primer in a document you are writing because there are named anchors in this guide use View Source in your browser to see the coding But if this document did not have named anchors you could not make a link to a specific section because you cannot edit the original file on NCSA s server Links to Specific Sections within the Current Document The technique is the same except the filename is omitted For example to link to the ANP anchor from within MaineStats enter More information about lt A HREF ANP gt Acadia National Park lt a gt is available elsewhere in this document Be sure to include the lt A NAME gt tag at the place in your document where you want the link to jump to lt A NAME ANP gt Acadia National Park lt a gt Named anchors are particularly useful when you think readers will print a document in its entirety or when you have a lot of short information you want to place online in one file Mailto You can make it easy for a reader to send electronic mail to a specific person or mail alias by including the mailto attribute in a hyperlink The format is lt A HREF mailto emailinfo host gt Name lt a gt For example enter lt A HREF mailto pubs ncsa uiuc edu gt NCSA Publications Group lt a gt to create a mail window that is already configured to open a mai
32. special meanings in HTML you must use their escape sequences amp 1t amp gt and amp amp respectively to enter these characters See the section Escape Sequences for more information Extended Quotations Use the lt BLOCKQUOTE gt tag to include lengthy quotations in a separate block on the screen Most browsers generally change the margins for the q lt P gt Omit needless words lt P gt lt BLOCKQUOTE gt uotation to separate it from surrounding text In the example lt P gt Vigorous writing is concise A sentence should contain no unnecessary words a paragraph no unnecessary sentences for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts lt P gt lt P gt amp mdash William Strunk lt BLOCKQUOTE gt the result is Omit needless words Jr 1918 lt P gt Vigorous writing is concise A sentence should contain no unnecessary words a paragraph no unnecessary sentences for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts William Strunk Jr 1918 TH A NCS Guid inners Guide eg to HTML Forced Line Breaks Postal Addresses The lt BR gt tag forces a line break with no extra white space between lines Using lt P gt elements for short lines of text such as postal addresses results in unwanted additional white space For example with National Center for Supercomputing Applicatio
33. stance 24 point bold Times centered The advantage of this approach it s similar in concept to style sheets in many word processors is that if you decide to change level one headings to be 20 point left justified Helvetica all you have to do is change the definition of the level one heading in your Web browser Indeed many browsers today let you define how you want the various HTML tags rendered on screen using what are called cascading style sheets or CSS CSS is more advanced than HTML though and will not be covered in this Primer You can learn more about CSS at the CSS site Another advantage of logical tags is that they help enforce consistency in your documents It s easier to tag something as lt H1 gt than to remember that level one headings are 24 point bold Times centered or whatever For example consider the lt STRONG gt tag Most browsers render it in bold text However it is possible that a reader would prefer that these sections be displayed in red instead This is possible using a local cascading style sheet on the reader s own computer Logical styles offer this flexibility Of course if you want something to be displayed in italics for example and do not want a browser s setting to display it differently you should use physical styles Physical styles therefore offer consistency in that something you tag a certain way will always be displayed that way for readers of your document Try to be consistent about which type
34. t Michigan lt LI gt Indiana lt UL gt lt UL gt The nested list is displayed as A few New England states m Vermont m New Hampshire Maine Two Midwestern states Michigan m Indiana Preformatted Text A Beginners Guide a to HTML TH fi Use the lt PRE gt tag which stands for preformatted to generate text in a fixed width font This tag also makes spaces new lines and tabs significant multiple spaces are displayed as multiple spaces and lines break in the same locations as in the source HTML file This is useful for program listings among other things For example the following lines lt PRE gt bin csh d SCR c 02 o mya out mysrc f a Out O S hse ea rm lt PRE gt display as bin csh cd SCR fs get mysrc f mycfsdir mysrc f fs get myinfile mycfsdir myinfile fs save myoutfile mycfsdir myoutfile cfs get mysrc f mycfsdir mysrc f cfs get myinfile mycfsdir myinfile fc 02 o mya out mysrc f mya out cfs save myoutfile mycfsdir myoutfile rm The lt PRE gt tag can be used with an optional WIDTH attribute that specifies the maximum number of characters for a line WIDTH also signals your browser to choose an appropriate font and indentation for the text Hyperlinks can be used within lt PR E gt sections You should avoid using other HTML tags within lt PR E gt sections however Note that because lt gt and amp have
35. t last header cell contents lt TH gt lt TR gt lt end of header row definition gt lt TR gt lt start of first row definition gt TD gt first row first cell contents lt TD gt lt TD gt first row last cell contents lt TD gt lt TR gt lt end of first row definition gt lt TR gt lt start of last row definition gt lt TD gt last row first cell contents lt TD gt lt TD gt last row last cell contents lt TD gt lt TR gt lt end of last row definition gt lt TABLE gt lt end of table definition gt You can cut and paste the above code into your own HTML documents adding new rows or cells as necessary The above example looks like hif when rendered in a browser The lt TABLE gt and lt TABLE gt tags must surround the entire table definition The first item inside the table is the CAPTION which is optional Then you can have any number of rows defined by the lt TR gt and lt TR gt tags Within a row you can have any number of cells defined by the lt TD gt lt TD gt or lt TH gt lt TH gt tags Each row of a table is essentially formatted independently of the rows above and below it This lets you easily display tables like the one above with a single cell such as Table Attributes soanning columns of the table A Tables for Nontabular Information Some HTML authors use tables to present nontabular information For example
36. tags will still be displayed however The Minimal HTML Document Every HTML document should contain certain standard HTML tags Each document consists of head and body text The head contains the title and the body contains the actual text that is made up of paragraphs lists and other elements Browsers expect specific information because they are programmed according to HTML and SGML specifications Required elements are shown in this sample bare bones document lt html gt lt head gt lt TITLE gt A Simple HTML Example lt TITLE lt head gt lt body gt lt H1 gt HTML is Easy To Learn lt H1 gt lt P gt Welcome to the world of HTML This is the first paragraph While short it is still a paragraph lt P gt lt P gt And this is the second paragraph lt P gt lt body gt lt html gt The required elements are the lt html gt lt head gt lt title gt and lt body gt tags and their corresponding end tags Because you should include these tags in each file you might want to create a template file with them Some browsers will format your HTML file correctly even if these tags are not included But some browsers won t So make sure to include them Click to see the formatted version of the example A Jonger exampldis also available but you should read through the rest of the guide before you take a look This longer example file contains tags explained in the next section Vv A Teaching Tool To see a co
37. title is also what is displayed on someone s hotlist or bookmark list so choose something descriptive unique and relatively short A title is also used to identify your page for search engines such as Google For example you might include a shortened title of a book along with the chapter contents NCSA Mosaic Guide Windows Installation This tells the software name the platform and the chapter contents which is more useful than simply calling the document Installation Generally you should keep your titles to 64 characters or fewer BODY The second and largest part of your HTML document is the body which contains the content of your document displayed within the text area of your browser window The tags explained below are used within the body of your HTML document Headings HTML has six levels of headings numbered 1 through 6 with 1 being the largest Headings are typically displayed in larger and or bolder fonts than normal body text The first heading in each document should be tagged lt H1 gt The syntax of the heading element is lt Hy gt Text of heading lt Hy gt where y is anumber between 1 and 6 specifying the level of the heading Do not skip levels of headings in your document For example don t start with a level one heading lt H1 gt and then next use a level three lt H3 gt heading Paragraphs Unlike documents in most word processors carriage returns in HTML files aren t significant In fact any
38. ts reserved 2003 Board of Trustees of the University of Illinois 26
39. u do not wish to slow down the loading of the main document with large inline images To include a reference to an external image enter lt A HREF MyImage gif gt link anchor lt A gt You can also use a smaller image as a link to a larger image Enter lt A HREF LargerImage gif gt lt IMG SRC SmallImage gif gt lt A gt The reader sees the SmallImage gif image and clicks on it to open the LargerImage gif file Use the same syntax for links to external animations and sounds The only difference is the file extension of the linked file For example lt A HREF AdamsRib mov gt link anchor lt A gt specifies a link to a QuickTime movie Some common file types and their extensions are plain text TXE HTML document html GIF image Kopki TIFF image LEE X Bitmap image xbm JPEG image Jpg or jpeg PostScript file ips AIFF sound file Jaakt AU sound file au WAV sound file wav QuickTime movie MOV MPEG movie mpeg or mpg Keep in mind your intended audience and their access to software Most UNIX workstations for instance cannot view QuickTime movies 20 TH A begs Guid inners Guide m to HTM Tables Before HTML tags for tables were finalized authors had to carefully format their tabular information within lt PRE gt tags counting spaces and previewing their output Tables are very useful for presentation of tabular information as well as a boon to creative HTML authors who use the table tags to pr
40. who might be visually impaired a necessity Images as Hyperlinks Inline images can be used as hyperlinks just like plain text This HTML code lt A HREF hotlist html gt lt IMG SRC hotlist gif ALT HOTLIST gt lt A gt produces the following result Note that this link doesn t actually go anywhere The blue border that surrounds the image indicates that it s a clickable hyperlink You may not always want this border to be displayed though In this case you can use the BORDER attribute of the IMG tag to make the image appear as normal Adding the BORDER attribute and setting it to zero lt A HREF hotlist html gt lt IMG SRC hotlist gif BORDER 0 ALT HOTLIST gt lt A gt produces the following result TH Beginners uide e N to HTM The BORDER attribute can also be set to non zero values whether or not the image is used as a hyperlink In this case the border will appear using the default text color for the web page For instance if you wanted to give your image a plain black border to help it stand out on the page you might try this lt IMG SRC hotlist gif BORDER 6 ALT HOTLIST gt And get the following result ae Background Graphics Newer versions of Web browsers can load an image and use it as a background when displaying a page Some people like background images and some don t In general if you want to include a background make sure your text can be read easily whe
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