SMIL files store multimedia presentation data in XML format. SMIL files define layout and other visual elements, including slide transition effects for created presentation. SMIL file can also store references to other streaming video or audio files included in presentation.

Four versions of SMIL exist: 1.0, 2.0, 2.1, and 3.0. Presentation created using Synchronized Multimedia Integration Language are verys similar to HTML pages. SMIL files are supported by Messaging tool installed by default on Nokia phones, for example, 3560 or 6600 models.