ASP.NET - What is DOCTYPE html PUBLIC ? why is XHTML used

Asked By anbu n on 22-Mar-13 02:46 AM
what is DOCTYPE html PUBLIC .... in aspx page?
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">

why is XHTML used ..... in aspx page ?
<html xmlns="">
azad chouhan replied to anbu n on 29-Mar-13 09:31 AM
doctype is an instruction to the web browser that in which version of  html page is written