H.264 is a next-generation video compression format. H.264 was evolved from MPEG-4 ASC. Developed for use in high definition systems such as HDTV, Blu-ray and HD DVD as well as low resolution portable devices such as Apple’s iPod, H.264 offers better quality at lower file sizes than both MPEG-2 and MPEG-4 ASP (DivX or XviD).
Apple has officially adopted H.264 as the format for QuickTime. It is also one of the formats chosen to be supported by both high definition DVD standards, and is destined to be the future standard format for Blu-ray.
H.264 is sometimes referred (erroneously) as x264 – x264 is the name of a popular freeware encoder for the H.264 format. H.264 is also sometimes referred to as MP4, again this is technically incorrect. MP4 is a container format much like AVI or MKV and it can be used to “house” many different types of compression codecs, not just H.264. It is true though that MP4 is a very popular choice for the H.264 format. MP4 should not be confused with MPEG-4 video either.