video/quicktime

Apple's .mov container, registered with IANA in 1993 and quietly the ancestor of half the video on earth — MPEG-4 Part 12 was built on the QuickTime atom structure, which is why .mov and .mp4 files are near-identical inside. Send it for .mov; browsers other than Safari often refuse it even when the codec inside is plain H.264 they would happily play from an .mp4. Modern files carry the ftyp box at offset 4 with the qt brand following, though pre-2001 movies can open straight with a moov or mdat atom instead.

.mov is universal; .qt survives only in the registration paperwork.

Defined by IANA registration — video/quicktime · IANA registration. Registry facts from the IANA media-types registry via mime-db.