The only official filename extension for MPEG-4 Part 14 files is. A separate hint track is used to include streaming information in the file.

Like most modern container formats, MPEG-4 Part 14 allows streaming over the Internet. It is most commonly used to store digital video and digital audio streams, especially those defined by MPEG, but can also be used to store other data such as subtitles and still images. MPEG-4 Part 14 or MP4, formally ISO/IEC 14496-14:2003, is a multimedia container format standard specified as a part of MPEG-4. MP4 to MOV - Convert file now View other video file formats Since stores like iTunes uses this container format, and it is used with iPod and PlayStation Portable (PSP), MP4 files have become more common.

MP4 is a container format that can store video, audio and subtitle data (as well as more depending on content). MP4 files (MPEG-4 Part 14) are multimedia files.