MP4 is a media container format which can store video and audio and other types of media.
When a viewer accesses an MP4, it typically appears as video supported by audio, but this is actually a collection of media files bundled together.
MP4s can also contain still photos or subtitles.
Despite the similar name, MP4 differs from MP3, which is an audio compression format using a specific type of compression. That format uses lossy data compression, which reduces the accuracy of certain parts of a sound file that most listeners are not capable of hearing anyway. This allows an MP3 to sound like the normal file for most listeners but occupy much less storage space.
MP4 can be compressed through a number of different codecs, on the other hand.
MP4 is often used in online video streaming and is based on the QuickTime File Format.
MPEG-4 Part 14 is another name for MP4.
