Designers transitioning to XHTML often get tripped up by the cryptic errors when validating. The W3C’s validator has long been lamented as being un–user–friendly.
Take the source of this very page. When everything is kosher, my XHTML 1.0 Transitional gets a thumbs up. But if I make a small, very understandable error like missing a </p> for example, look what happens. I missed one closing tag, and received 52 validation errors.
The enthusiasm of a beginning web designer getting her feet wet with XHTML rapidly wanes when this happens to her. Seeing so many errors on one page is a blow to one’s psyche, and when they don’t realize that all 52 can be eliminated with the addition of four bytes to their code, it can make the difference between sticking it out until validation is achieved, and turning their back on valid markup because it’s just too hard.
update: Zeldman has pointed out that the validation services are maintained by a small, unpaid and under–appreciated staff of volunteers who are looking for help to improve the service. It’s not fair of me to point out the shortcomings of a group that is doing so much with so little, especially out of my own ignorance, so I’ve toned down the original post. Hopefully my criticism comes across as more constructive than otherwise…
If you have the time and technical expertise necessary, this would be a great project to get involved with. My personal gratitude to those working on this necessary tool.