What's the latests HTML ? Remember there was HTML 2.0 ... then IE came with HTML 3.0 ... then HTML 4.0 ... then HTML 5.0 from when that X.0 came out anyway ? from the version of internet explorer?!
xHTML 1.1 is the most up to date standard however w3 recently formed a working party to start discussing xHTML 2.0
It is not the latest standard. It is a concurrent standard that co-exists along with HTML 4.01. HTML 5 is a joke. Originally designed as an independent initiative to streamline and clean up the HTML specification while giving more semantic meaning to the elements in the specification, it has since been riddled by idiots who have no place being anywhere NEAR a computer in the first place adding bullcrap that shouldn't even be there anyway (such as presentational elements and attributes). As for XHTML, it's merely a reformulation of HTML 4.01 as an XML application. However, while XHTML 1.1 may be the latest "flavor" it is not ready for practical deployment, since 80% of the browsers installed (read: Internet Explorer) don't understand XHTML and will force a file download rather than render the Web page, so if you use XHTML, use XHTML 1.0 instead. It doesn't matter whether you use HTML 4.01 or XHTML 1.0 but make sure you use a Strict DOCTYPE and that your code validates. If you're going to use old, deprecated and obsolete code such as target="" or <font> then use a Transitional DOCTYPE instead, but bear in mind that "Transitional" != complete. It's meant to "make the transition to" clean, minimal, semantic and valid markup that separates the structure (HTML) from the presentation (style).