You may see files with extensions like .m4a (audio only) or .m4v (often used by Apple for video with DRM protection), both of which are based on the same Part 14 standard.
MP4 is the file format (the container), whereas MPEG-4 is the broad standard that includes various compression methods. 19448mp4
Unlike simple video files, MP4 is a "multimedia container." It can store video, audio, subtitles, and still images all in one file. You may see files with extensions like
MP4 typically uses the H.264 (AVC) or H.265 (HEVC) codecs for video and AAC for audio. 19448mp4
It is designed to provide high-quality video at relatively small file sizes, making it the "gold standard" for internet streaming and YouTube.