HTML and CSS Reference
In-Depth Information
XHTML 1.0 and HTML 4.01
Most web pages that exist today were created to conform to the XHTML 1.0 or
HTML 4.01 specifications. Many of them are not actually valid but work fine in the
popular browsers. So if you're working on an existing website, chances are you'll be
working with pages in one of these two formats.
XHTML defines HTML so that it conforms to the XML specification. When you want to
know whether a particular tag or attribute is valid, check out the HTML specification.
When you want to know how to close a tag that has no closing tag, such as <br> , consult
with the XHTML spec. In earlier lessons, you learned about the various flavors of
HTML 4.01 and XHTML 1.0 and how each of them is geared toward users of older or
newer browsers:
HTML 4.01 or XHTML 1.0 Transitional —For those who want to provide sup-
port for older browsers
HTML 4.01 or XHTML 1.0 Frameset —For sites that want to use frames in a
standards-compliant manner
HTML 4.01 or XHTML 1.0 Strict —For those who want to develop pages that
strictly adhere to the HTML 4.0 or XHTML 1.0 specification by not using depre-
cated elements or attributes
You may encounter these three DOCTYPEs when you work on existing pages, or if you
want to create a site that uses frames, you'll need to use one of the two frameset
What Is Accessibility?
Accessibility is basically the effort to make websites as usable as possible for people with
disabilities. This involves the creation of software and hardware that enables people with
various disabilities to use computers and the Web. It also means addressing accessibility
concerns in the design of HTML as a markup language and efforts on the part of web
designers to incorporate accessibility into their websites. When a person with impaired
vision uses a screen reader to visit a website, there are things the site's author can do to
make that experience as rich and fulfilling as possible given the user's disability.
Common Myths Regarding Accessibility
Historically, there has been some resistance among web designers toward building web-
sites in an accessible manner. This resistance has arisen not due to a want to discriminate
against people who might benefit from accessible design, but rather from a fear that
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