An H264 file is a video file encoded with H.264 compression, which is a popular format for high definition video. It is often used as the video format for AVCHD camcorders, HDTV, Blu-ray, and HD DVD. H264 generally refers to a video file that is an .MP4 file.

H.264 is actually a video compression codec that requires a video container to host the encoded video. Therefore, a file with the .h264 extension may be a misnamed a .264 file or .MP4 file (or another supporting container file format such as .AVI or .MKV). Nevertheless, the .h264 extension is still sometimes used to describe the contents of H.264 encoded video files.