We here at Pixelfind do everything necessary to keep our work up-to-date with existing technologies.
But, working mainly in the field of webdesign, we must respect it's laws. One of them is the requirement for a valid HTML/XHTML document.
Where do we validate our documents? In the W3C Validator you can find here: http://validator.w3.org/
We recommend that you new programmers working in any technology that outputs HTML pages, validate those pages, to assure it is up to the standard.
Cosmin | Pixelfind