XHTML+SMIL adds timing and media synchronization support to XHTML pages. It integrates the SMIL language into the XHTML language. Using a few SMIL elements and attributes, it is possible to add images, video, and sounds to an XHTML page, and synchronize them with XHTML text elements over a specified amount of time. In short, you can use XHTML+SMIL technology to quickly create multimedia-rich, interactive presentations, and view them in a web browser without installing a SMIL player.
