Web Development and Design Foundations with XHTML, 5th Edition

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Comparison of

HTML 4, XHTML,

and HTML 5

As you traverse the Web and view the source codeof

pages created by others, you may notice that the style and syntax of the coding

is different from the XHTML syntax that you have been studying. Most likely,

those pages were written following HTML syntax.

XHTML, eXtensible HyperText Markup Language, uses the tags and attributes

of HTML along with the syntax of XML (eXtensible Markup Language). For

the most part, you will use the same tags and attributes in HTML and

XHTML; the major change is the syntax and additional restrictions in

XHTML. These restrictions were added so that more efficient programs could

be written to process Web pages automatically. XHTML 1.0 Transitional is

backward compatible with HTML 4.01, commonly referred to as HTML 4.

Most Web pages currently use HTML 4 or XHTML 1.0 Transitional. However,

it is good to be aware of the trends in XHTML. At the time this was written,

the W3C was in the process of drafting HTML 5.

In this section we’ll concentrate on the differences between HTML 4, XHTML,

and HTML 5—introducing you to some specific examples of syntax differences

between HTML, XHTML, and HTML 5. Note that HTML 5 has two different

acceptable syntaxes: HTML syntax and XHTML syntax. See http://dev.w3.org/

html5/html-author for more information about writing HTML 5 documents.

D.1 XML Declaration

Since XHTML follows XML syntax, each document should begin with an

XML declaration. HTML 4 has no such requirement.

HTML 4

Not required

D

APPENDIX