SMIL - Protocol
Short for Synchronized Multimedia Integration Language, a new markup language being developed by the World Wide Web Consortium (W3C) that would enable Web developers to divide multimedia content into separate files and streams (audio, video, text, and images), send them to a user's computer individually, and then have them displayed together as if they were a single multimedia stream. The ability to separate out the static text and images should make the multimedia content much smaller so that it doesn't take as long to travel over the Internet.
SMIL is based on the eXtensible Markup Language (XML). Rather than defining the actual formats used to represent multimedia data, it defines the commands that specify whether the various multimedia components should be played together or in sequence.