MP4, MOV, MXF, WAV… what they hold, where they play.
Explains the containers: the boxes that hold picture, sound, timecode and subtitles (.mp4, .mov, .mxf, .wav…). Start from what you want to do: the containers that fit light up; tap one for its card: extensions, what it can hold, timecode, subtitles, where it plays.
The Codecs link opens it on a typical codec of that container; Codecs links back here. At the bottom, a short glossary.
The cards stick to stable, well-known facts; what a file really contains depends on the camera or the software that made it (the Media info tool reads it).
Free, no account, nothing is sent: it runs in your browser, even offline.