Difference html and xhtml

HTML allows single tags such as <IMG> while the XML standard that XHTML is based off of does not. Instead, XML uses another syntax for empty (double) tags that looks like <IMG/> with the slash at the end of the tag.XHTML is the new standard for HTML coding. It requires that all tags must be closed (even one tag ones like <br /> and <img ... />) It also requires that all tags and attributes be lowercased and double quotes (") be used around the attributes. For more info on HTML standards go to http://www.w3c.com/