Synchronized Multimedia Integration Language (SMIL (/ˈsmaɪl/)) is a World Wide Web Consortium recommended Extensible Markup Language (XML) markup language to describe multimedia presentations. It defines markup for timing, layout, animations, visual transitions, and media embedding, among other things. SMIL allows presenting media items such as text, images, video, audio, links to other SMIL presentations, and files from multiple web servers. SMIL markup is written in XML, and has similarities to HTML.
As of 2008, the W3C Recommendation for SMIL is SMIL 3.0.
SMIL 1.0 became a W3C Recommendation in June 1999.
SMIL 2.0 became a W3C Recommendation in August 2001. SMIL 2.0 introduced a modular language structure that facilitated integration of SMIL semantics into other XML-based languages. Basic animation and timing modules were integrated into Scalable Vector Graphics (SVG) and the SMIL modules formed a basis for Timed-Text. The modular structure made it possible to define the standard SMIL language profile and the XHTML+SMIL language profile with common syntax and standard semantics.
SMIL 2.1 became a W3C Recommendation in December 2005. SMIL 2.1 includes a small number of extensions based on practical experience gathered using SMIL in the Multimedia Messaging System on mobile phones.
SMIL 3.0 became a W3C Recommendation in December 2008. It was first submitted as a W3C Working draft on December 21, 2006. The last draft revision was released on October 6, 2008.