MPEG standards for dummies : this is an over simplified vision. Hopefully, as the time goes these standards defined files type, audio or video codecs, are mainly used by the Industry. 

The MPEG standard has several chapters: generally Chapter 2 describes how the video codec works  and Chapter 3 the audio codec.

MPEG Standards

Notes

• MP3 is part of MPEG 1 and MPEG 2 standards
• The AAC is part of MPEG 2 and MPEG 4 standards

Containers

In the first place, MPEG standards offer various containers used in the Industry of audio and video broadcasting.

• MPEG elementary stream : are only audio and video MPEG files, they have for file extension : m1v, m2v, m4v, mp3
• MPEG Program stream : are muxed (multiplexed) audio/video files, and it’s file extension is : mpg, dat, m2p, vob
• MPEG Transport stream : are muxed MPEG  audio/video files sliced for broadcasting, it’s file extension: m2t, m2ts (BluRay), mts. 

 Then there are all the other computer containers. For example: a video encoded in H264 with AAC sound.

it can take place in those containers: mov, f4v, mp4, m4v, mts