HTML and CSS Reference
4.3. Changing Text Appearance and Meaning
A number of tags change the appearance of and associate hidden mean-
ing with text. In general, these tags can be grouped into two flavors:
content-based styles and physical styles.
In addition, the World Wide Web Consortium (W3C) standard for Cascad-
ing Style Sheets (CSS) is now well supported by the popular browsers,
providing another, more comprehensive way for authors to control the
look and layout of their document text. We describe the tag-based text
styles in this chapter. See Chapter 8 for details about CSS.
4.3.1. Content-Based Styles
Content-based style tags inform the browser that the enclosed text has
a specific meaning, context, or usage. The browser then formats the text
in a manner consistent with that meaning, context, or usage. Note the
distinction here. Content-based style tags confer meaning, not format-
ting. Accordingly, they are important for automated processes; machines
don't care what the document looks likeat least for now.
Because font style is specified via semantic clues, the browser can choose
a display style that is appropriate for the user. Because such styles vary
by locale, using content-based styles helps ensure that your documents
will have meaning to a broader range of readers. This is particularly
important when a browser is targeted at blind or handicapped readers
whose display options are radically different from conventional text or
are extremely limited in some way.
The current HTML and XHTML standards do not define a format for each
content-based style; they only specify that they must be rendered in a
manner different from the regular text in a document. The standards
don't even insist that the content-based styles be rendered differently
from one another. In practice, you'll find that many of these tags have
fairly obvious relationships with conventional print, having similar mean-
ings and rendered styles, and are rendered in the same style and fonts
by most browsers.