HTML and CSS Reference
Listing 3-6. An XHTML 1.1 Skeleton Document
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
<title>XHTML 1.1 sample document title</title>
<meta http-equiv="Content-Type" content="application/xhtml+xml; charset=utf-8" />
XHTML 1.1 sample document body
XHTML 1.1 can also be used in mixed-namespace documents to support mathematical markup and vector
graphics (see “XTHML+MathML+SVG”).
XHTML 2.0 (also denoted as XHTML2) could have been the next-generation markup language and the successor of
XHTML 1.0 and 1.1. However, it remained on the Working Draft level and never became a Recommendation.
Although XHTML 2.0 reused elements from earlier versions of markup languages, it had backward compatibility
issues. However, web designers familiar with XHTML 1.0 and 1.1 could easily develop XHTML 2.0 documents.
The “Modularization of XHTML” refers to XHTML 2.0 as not just another markup language but as an XHTML host
language . In XHTML 2.0, there were several updated modules compared to the “Modularization of XHTML.”
After the W3C shifted its focus from XHTML 2.0 to HTML5, many features originally introduced in the XHTML 2.0
working draft were assigned to independent working groups to continue their development (RDFa, XForms, XML
HTML5 was initially proposed by individuals from Apple, the Mozilla Foundation, and Opera Software, known as
the Web Hypertext Application Technology Working Group ( WHATWG ) . Later, the W3C validated the WHATWG
proposal and announced to work on a new HTML specification . WHATWG found XHTML 2.0 too document-
centric and inappropriate for blogs, forums, web stores, and multimedia sites. Their major goal was to create a
platform for dynamic web applications .
While its name might be misleading, HTML5 is not just another HTML language. It is the complete reformulation
of former markup languages with new capabilities. HTML5 is designed to be backward-compatible with older
browsers, and uses a syntax that is compatible with both HTML and XHTML documents. In HTML5, you can use the
well-known text/html media type, or a new media type called text/html-sandboxed , which makes it possible to
interpret a file without giving the content access to the rest of the web site. Because of a new approach that separates
authoring and rendering conformance requirements, deprecated tags are not needed anymore.
All modern browsers released in or after 2012 have good HTML5 support. The HTML5 support of older browsers
can be tested with services such as the “HTML5 test” for backward compatibility . For those who want to
contribute to the development of HTML5, several tests are available on the W3C testing web page, where current tests
can be reviewed and new tests submitted .