Many developers are choosing to use XHTML instead of HTML as they move towards web standards. Some of these developers use XHTML without looking at all the issues.
My advice to anyone thinking about using XHTML would be to read all the information you can on the advantages and disadvantages of XHTML so that you can make an informed decision.
If you feel that XHTML is the most appropriate choice, you will then be faced with the "MIME type challenge" which is:
XHTML 1.0 (transitional, frameset or strict) should be served as application/xhtml+xml.
Internet Explorer does not support the application/xhtml+xml MIME type.
To solve this MIME type challenge, you then have to choose one of the following options:
Ignore the issue completely and use XHTML served up as text/html.
Use XHTML served up as text/html using backward compatibility mode.
Use XHTML served up as application/xhtml+xml and deal with Internet Explorer using content negotiation.
There are many detailed articles that explain the issues associated with these three choices:
- Sending XHTML as text/html Considered Harmful
- XHTML's Dirty Little Secret
- XHTML is dead
- Content negotiation
- Pretending to use XHTML
- Quick guide to XHTML
- The perils of using XHTML properly
At the risk of being burned at the stake, I think that unless you are willing to serve your pages as application/xhtml+xml with content negotiation, then you are probably better off staying with HTML 4.01 at this time.
I prefer HTML 4.01 Strict over HTML 4.01 Transitional, as it forces developers to separate content and presentation more fully than Transitional. For example, presentational attributes such as align, background, bgcolor, border (for images and objects), clear, color, face, hspace and many others are allowed in Transitional, but not in Strict. Using Strict also forces developers to structure and mark up content more thoughtfully as you cannot have inline content directly inside the body, blockquote or form elements.
The bottom line is that each developer has to make their own choices.