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HTML & XHTML: The Definitive Guide, 6th Edition by Bill Kennedy, Chuck Musciano

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Tags and Attributes

For the most part, tags—the markup elements of HTML and XHTML—are simple to understand and use, since they are made up of common words, abbreviations, and notations. For instance, the <i> and </i> tags respectively tell the browser to start and stop italicizing the text characters that come between them. Accordingly, the syllable "simp" in our barebones example in Figure 3-1 should appear italicized when displayed by the browser.

Compare this browser display with its Barebones source HTML shown earlier

Figure 3-1. Compare this browser display with its Barebones source HTML shown earlier

The HTML and XHTML standards and their various extensions define how and where you place tags within a document. Let's take a closer look at that syntactic sugar that holds together all documents.

The Syntax of a Tag

Every tag consists of a tag name, sometimes followed by an optional list of tag attributes, all placed between opening and closing brackets (< and >). The simplest tag is nothing more than a name appropriately enclosed in brackets, such as <head> and <i>. More complicated tags contain one or more attributes, which specify or modify the behavior of the tag.

According to the HTML standard, tag and attribute names are not case-sensitive. There's no difference in effect between <head>, <Head>, <HEAD>, and even <HeaD>; all of them are equivalent. With XHTML, case is important: all current standard tag and attribute names are in lowercase; always ...

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