Encyclopedia of Computer Science and Technology

232 HTML, DHTML, and XHTMLFurther Reading“Grace Brewster Murray Hopper” [biography]. St. Andrews University[Scotland] School of Mathematics and Statistics.Available online. URL: http://www-history.mcs.st-andrews.ac.uk/Biographies/Hopper.html. Accessed August 7, 2007.Grace Hopper Celebration of Women in Computing. Availableonline. URL: http://gracehopper.org. Accessed August 7, 2007.Marx, Christy. Grace Hopper: The First Woman to Program the FirstComputer in the United States. New York: Rosen PublishingGroup, 2003.Williams, Kathleen Broome. Grace Hopper: Admiral of the CyberSea. Annapolis, Md.: Naval Institute Press, 2004.HTML, DHTML, and XHTMLIn developing the World Wide Web, Tim Berners-Lee (seeBerners-Lee, Tim) had to provide several basic facilities.One was a protocol, HTTP, for requesting documents overthe network (see world wide web). Another was a systemof links between documents (see hypertext and hypermedia).The third was a way to embed instructions in thepages so that the Web browser could properly display thetext and graphics. Berners-Lee created HTML (HypertextMarkup Language) for this purpose. It is based on the moreelaborate SGML (Standard Generalized Markup Language).The basic “statement” in HTML is the tag. Tags aredelimited by angle brackets (). Tags that affect a documentor section of a document come in pairs, with the secondmember of the pair preceded by a slash. For example,the tagsindicate the beginning and end of an HTML document,while and delimit text that should berendered in boldface.Besides specifying such things as headings, font, fontsize, and typestyles, HTML includes tags for Web-relatedfunctions. One of the most useful is the A, or “anchor”tag. As with some other HTML tags, the A tag is used withattributes that further specify what it so be done. The A tagis usually used with the or Hypertext Referenceattribute, which specifies a document that is to be linked tothe current document so that the user can click on a highlightto go there. For example:Glossary of Computer Termsspecifies a link to a particular page at a particular site.The link will appear in the browser as the highlighted textGlossary of Computer Terms. If clicked, the browser willload the HTML page titled Glossary.Implementation and ExtensionsInserting HTML tags by hand is a tedious and error-proneprocess (for example, it’s easy to omit a bracket or a slashor add “illegal” spaces within tags). Fortunately, there arenow many HTML editor programs that let users insert theappropriate elements much in the way word processorsmake it easy to specify fonts and formatting. (Indeed, programssuch as Microsoft Word allow users to convert andsave documents in HTML format.)HTML has been extended in a number of ways. First,new features have been added to later versions of the lan-An HTML hyperlink embedded in a Web page. The anchor link gives the address (URL) of the linked page, as well as specifying the text thatwill appear in the link, which will be rendered by the Web browser in a special color or font.