Join Bill Weinman for an in-depth discussion in this video Understanding versions of HTML and XHTML, part of XHTML and HTML Essential Training.
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There are a number of versions of HTML and XHTML available. Let's take a look at them. HTML 4.01 is the current version of HTML. It has been in use since 1999 and it is still standard today. XHTML 1.0 is based on HTML 4.01. It is in wide use today for working websites. It's easy to use and most sites that are XHTML use 1.0. XHTML 1.1 is a very strict and stripped down version of XHTML.
It has no presentation features. Instead, you must rely on CSS style sheets to do all your layout. Unfortunately, not all browsers implement CSS with sufficient consistency to make this work in all cases. So, sites that use XHTML 1.1 are still pretty rare and for good reason. XHTML 2.0 began in 2002 and was actively in development until 2006. As of this recording, it's been pretty much abandoned. XHTML 2.0 was designed to be a clean break from HTML with no requirement for backward compatibility.
This never worked very well. The browser companies weren't really very interested in it. So it has substantially failed. HTML 5 picks up where XHTML 2.0 left off, except that it is backward compatible. It has a lot of exciting new features including XForms, which extend the capabilities of HTML forms to include more data types, better formatting, data validation and many other useful features. XForms has been around since 2003 and is now in its second full version, but it is not yet adopted by any of the major browsers.
Where it's relevant? I'll discuss how examples relate to HTML 4, but I'll always show you the strictness to most compatible XHTML 1.0, so that you know how to make your websites functional, compatible and attractive.
- Understanding the structure of an HTML or XHTML document
- Creating and using templates
- Controlling white space and line breaks
- Making effective use of tables and frames
- Flowing text around an image
- Formatting tables with CSS
- Creating web pages that work properly across platforms and devices
- Reviewing a case study of a complete web site