.smil

Multimedia presentation written in the Synchronized Multimedia Integration Language (SMIL), which is similar to HTML; used for developing audiovisual slide shows and presentations; may contain text and references to streaming audio and video files.

The SMIL format is supported by various Nokia cell phones, such as the Nokia 6600, 3560, and other Series 60 (S60) phones. SMIL files can be created and opened by the Messaging Application included with the phone's software.

Additional information about the SMIL format can be found at the W3C website.