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Hypertext Markup Language (HTML)
Introduction:
Hypertext Markup Language (HTML) consists of a library of tags that can be embedded in plain-text documents. When they are correctly inserted in a document, it should display correctly on any browser for DOS/Windows, Unix, or the Macintosh. This document discusses certain settings you may need to make in Windows, and so assumes you are using a DOS machine. But the following discussion of the tags inside a document should pertain to any HTML document.
HTML tags permit the usual word-processing functions, such as highlighting text, changing fonts, formatting ordered lists, and so on. All word-processing markup languages permit this. But HTML tags also let you link to documents and services on the Internet. This includes documents, images, sounds, animated sequences, and Telnet/FTP sessions with other servers on the Internet. The true importance of HTML is that the tags were designed to exploit world-wide client-server architecture. The telecommunications protocols between all those servers and the client on your desktop is "transparent" to you; they are handled automatically by an HTML tag like "http." To read a document specifically about the client-server paradigm, click on the highlighted phrase. To read a document specifically about the WWW, single-click your mouse cursor on WWW.
HTML resembles the GML (Generalized Markup Language) tags you may have worked with in other word-processing languages, such as Script's SGML tags. When a document is formatted with HTML tags, and your browser requests the document from an HTTP server, the browser interprets the tags in the document, the text they affect is formatted, and then the tags are discarded. They do not appear in the output document that is displayed on-screen or printed.
Starting Simply: Highlighting Text
HTML can be used as a word processing language in documents stored locally on your own hard drive. You can view them through a WWW browser, like Netscape or Microsoft's Internet Explorer, without ever inserting any of the tags that will make them viewable from The Web. Tags are available for highlighting text, such as making it bold, italic, or underscored. You can insert them manually with any editor of your choosing, such as DOS Edit, or Kedit, or Windows' Notepad, or you can use one of the special editors that automates HTML tag insertion.
Hypertext Links to Other Documents:
Other HTML tags let you link to external documents; in effect, they can convert your document into a "launching pad" to an impressive array of electronic services all over the world. One of these simpler tags connects you to another document on a server of your choosing. For example, move your mouse cursor to ASCII, which is a separate how-to document for displaying symbols in your documents that you cannot type in from the keyboard, such as degree signs, superscripts, etc. Notice the message that flashes at the bottom of your screen: that is the document's URL, or Uniform Resource Locator, which was discussed in the WWW document hotlinked above.
You do not need to link to an entire document; you can link to only a section if you wish. Suppose we want to link to the section on "The Hypertext Concept" in the World Wide Web document that you linked to in its entirety above. First, insert a named link like this just before the target text in the document you are linking to: <a name="Introduction"></a>
Now, by clicking on partial link , you can save time by linking to a specific target within the document, our preceding Introduction in this case. Use the browser's Back key to return to your beginning point.
Hypertext Links to Images
Another type of hypertext link is to an image. The first SIU logo you see is an "inline image," or one that is a permanent part of the document. You have no choice about whether the image displays when you retrieve the document. Such inline images drastically increase the size (in bytes) of a document, which correspondingly increases transmission time from server to client and storage size in the client's disk and memory.
Another method for displaying images is to insert a hotlink in the document and let the client decide whether to display the image. Move your mouse cursor to the phrase SIU Logo. Click anywhere on the highlighted phrase, and another copy of the SIU Logo image will be generated. Whatever viewer you have defined for your browser will be assigned to interpret the image the server has sent to your client; it may wrap its frame around the image. You should be able to drag this image around your screen, resize it, or apply any other function your particular viewer allows. same hotlink. Double-click on its corner to close it.
You can also link to an image from an image, or to a document from an image. This copy of the SIU logo is also an inline image, but it has a hypertext link behind it to a copy of another SIU logo. Click on it to display it. This larger copy of the logo, like the preceding example, is not a permanent part of the document; it was called from a server on campus.
Hypertext Links to Other Servers:
You can also link to other servers. For example, to link to the SIUC Intranet page, click on Intranet. You can logon to your mainframe account by clicking on mainframe.
Nested Lists:
Nested lists can be created like this:
Unordered Lists
Item One
- Item Two
Thousands of web pages offer much more extensive sources of information about HTML than this brief summary. Use the Computer Support Center's search page to search on a target like HTML. Two sample sites a typical search turned up are:
