What is HTML?The simple answerHTML is the language that Web pages are written in. HTML stands for HyperText Markup Language. I know about hypertext, but... "markup language"?To explain this, I need to give you a little more background information. Hold on; this part can be confusing at first! "Markup" basically refers to the text that you insert into a document to indicate how the file should be displayed or printed. If you've used Word Perfect (especially back in the old DOS days), you may have used a program mode called "Reveal Codes." With Reveal Codes turned on, you could see a whole bunch of little codes interspersed in your document's text. There might be a code that meant, essentially, "This is where a paragraph begins," or a code that meant "Put a line break here," or a code that meant "Make this text boldface." These codes are markup code. Usually, the codes are called "tags." SGMLSGML (Standard Generalized Markup Language) has been created to be a standard description of how to define a document markup language. HTML (among others) is a language based on this specification. The basic concept behind SGML is that all documents have a certain logical structure, which can be described without any reference to how that structure should look, physically. Markup tags are used to define the elements of the logical structure. For example, one element might be defined as a "Paragraph," and another might be defined as a "Heading." In fact, the look of the document can and will change depending on what type of system it is being viewed on, what settings the user prefers, and so on. The visual appearance of the document is secondary to the textual content of the document. The importance here is to communicate the message and not to worry about whether it looks good. (Perhaps this means that the designers of SGML weren't very visually-oriented -- because the look of a document often is part of the message. But hold that thought for a while -- we'll come back to it later.) Why would you want to do this? Well, it allows you to separate a document's structure and content from its appearance. Appearance is fickle. Fashions and looks change. If you can redo the look of a document without changing the rest of the content, it saves you a lot of time and hassle. Another benefit to this is that it makes documents more "portable" -- that is, they are usable in more ways. You can view them on different computer systems, print them out, and run them through a text reader for the blind or a Braille generator. Each system that processes marked-up documents will have its own way of processing the content. A phrase marked "Heading" might be displayed as boldface on a Mac, underlined and centered on an old DOS 386, spoken with a deep tone of voice on a text reader, or printed in red when run through a printer. Each system will diaply the text differently, but each system will also make it clear, one way or another, that the text is a "Heading." This is useful for the Web, because the WWW itself was originally intended to be cross-platform, that is, viewable on any computer system. The beauty of the Web is that, in theory, a particular web page can be understood by a person running a brand-new PentiumIII, a person with an iMac, a person running a Unix workstation, or even a blind person with a text reading system. In practice, this doesn't always happen, and we'll get to that later on -- but the original intention of the WWW was to be platform non-specific -- anyone could make use of it. HTMLHTML is based on SGML. HTML is the markup language that we use to make Web pages, to be displayed in a Web browser. (A Web browser is a software program that reads Web pages and displays them to you. The most common Web browsers are Netscape Navigator and Microsoft Internet Explorer, but there are many others, including Lynx, Opera, WebTV, and ICab. Browsers aren't just found on desktop computers -- you might have seen the commercials advertising Web access on a cell phone, or a Palm Pilot handheld organizer.) HTML tags are placed in a document, to describe the structure and appearance of the document. The Web browser then reads the document, and displays it as best it can, based on the HTML tags it finds there. As you might imagine, a page is going to look very different on a Palm Pilot or a cell phone than it does on an iMac. (Not to mention a text reader, which "displays" documents in an entirely different way.) In the next section, I'll show you what HTML looks like. |