You probably noticed right away, perhaps in surprise, that the browser displays less than half of the example source text. Closer inspection of the source reveals that what’s missing is everything that’s bracketed inside a pair of less-than (<) and greater-than (>) characters.
HTML and XHTML are embedded languages: you insert their directions, or tags, into the same document that you and your readers load into a browser to view. The browser uses the information inside those tags to decide how to display or otherwise treat the subsequent contents of your document.
For instance, the tag that follows the word Hello in the simple example tells the browser to display the following text in italics.
[*] Italicized text is a very simple example and one that most browsers, except the text-only variety (e.g., Lynx), can handle. In general, the browser tries to do as it is told, but as we demonstrate in upcoming chapters, browsers vary from computer to computer and from user to user, as do the fonts that are available and selected by the user for viewing HTML documents. Assume that not all are capable of or willing to display your HTML document exactly as it appears on your screen.
The first word in a tag is its formal name, which usually is fairly descriptive of its function, too. Any additional words in a tag are special attributes, sometimes with an associated value after an equals sign (=), which further define or modify the tag’s actions.