From Forensics Wiki

The Joint Photographic Experts Group (JPEG) format is a commonly-used lossy image format.

Format

JPEG is a container file format that consist of a well defined header, some metadata, icons, a color table, compressed data, and a well defined footer. The header is usually FF D8 (hex).

Common file extensions are .jpg, .jpeg, .JPG, .JPE, and .jfif.

Metadata

JPEG files can contain lots of metadata in several formats: Exif, IPTC, GPS, Camera Raw, etc. The exif and jhead command tools can extract and manipulate some of that metadata. Adroit Photo Forensics can be used to extract, view and group metadata from jpeg and camera Raw files.

Externals Links

• Wikipedia: JPEG
• Article about hidden data in JPEG files (Exif, digital fingerprint, etc.)