SMIL (Synchronized Multimedia Integration Language), is a language that allows Web site creators to be able to easily define and synchronize multimedia elements (video, sound, still images) for Web presentation and interaction. On today's Web, although you can send moving and still images and sound to a Web user, each element is separate from the others and can't be coordinated with other elements without elaborate programming. SMIL (pronounced "smile") lets site creators send multiple movies, still images, and sound separately but coordinate their timing. Each media object is accessed with a unique Uniform Resource Locator (URL) which means that presentations can be made of objects arriving from more than one place and that objects can easily be reused in multiple presentations.
SMIL also lets the "producer" store a media object in multiple versions, each with a different bandwidth so that a lower-bandwidth version of a Web page can be sent to users who need it. SMIL also accommodates multiple language versions of soundtracks.
SMIL statements are simple and can be entered with a text editor similar to those used to create Hypertext Markup Language (HTML) pages. A presentation can be described using only three Extensible Markup Language (XML) elements. It's intended that SMIL will be usable by anyone who can use HTML.
SMIL was developed by a group coordinated by the World Wide Web Consortium (W3C) and included representatives from the CD-ROM, interactive television, Web, and audio/video streaming industries. The first public draft of SMIL was released in November, 1997.