XHTML stands for EXtensible
Hyper Text Markup
Language and it is a stricter and cleaner version of HTML
recommended by W3C (World Wide Web Consortium). XHTML is the effective inheritor
of HTML 4.01 and although it is almost identical to its predecessor it is aimed
to replace it. There are three levels of XHTML compliance (sorted by importance in a descending order):
All Telerik ASP.NET AJAX controls are XHTML 1.1 compliant except for RadChart, which is XHTML 1.0 Transitional compliant.