XHTML™ 1.0: The Extensible HyperText Markup Language

A reformulation of HTML 4 in XML 1.0. This is my favorite part, from the Differences with HTML 4 section: “4.1 Documents must be well-formed.” Good luck! Anyway, this is how Jeffrey Zeldman summed it up: “One language (like HTML, but better) that lets you create sites that work on cell phones as well as the desktop. Sites that can include text, database functionality (think: Amazon.com) and even lush media like moving images and music. The next few years should be very interesting.”