The latest HTML standard is XHTML 1.1. This version is based on the XHTML 1.0 Strict version with the following differences:
These changes mean that pages coded to use this standard may use a number of tags not recognised by current browsers as well as not being able to use tags that are recognised by the browsers. As such, it is probably too early to start coding your pages using this standard yet. Maybe in another year or two.
For more information about XHTML 1.1 visit W3C.
If you do decide to code to this standard then you should code your doctype statement as described below. Remember that HTML is case sensitive so the declaration should be exactly as shown.<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
This article written by Stephen Chapman, Felgall Pty Ltd.