image/jpeg

The photograph format, registered with MIME itself in 1996 and still what most cameras write first. Send it for photos and anything with continuous tones; send PNG instead for screenshots and line art, where JPEG's lossy blocks smear text. The persistent mislabel is image/jpg — no standard defines it, and while browsers shrug it off, strict content negotiation and some upload validators do not. On the wire it means JFIF or Exif data, both of which start with the same three marker bytes.

.jpg exists because DOS filenames allowed three letters; .jpeg and .jpg are the same format, and .jpe is the even rarer fossil of the same era.

Defined by RFC 2046 · IANA registration. Registry facts from the IANA media-types registry via mime-db.