JPEG is a commonly used standard method of compression for photographic images. The name JPEG stands for Joint Photographic Experts Group, the name of the committee who created the standard. The group was organized in 1986, issuing a standard in 1992 which was approved in 1994 as ISO 10918-1. JPEG should not be confused with MPEG, the Moving Picture Experts Group, which produces compression schemes for motion pictures.

JPEG provides for lossy compression of images (although there are variations on the standard baseline JPEG which are lossless). The file format which employs this compression is commonly also called JPEG; the most common file extension for this format is .jpg, though .jpeg, .jpe, .jfif and .jif are also used.

JPEG itself specifies both the codec defining how an image is transformed into a stream of bytes, and the file format used to contain that stream. The file format is known as 'JPEG Interchange Format' (Often confused with the JPEG File Interchange Format), and is specified in Annex B of the standard. It is possible for JPEG data to be embedded in other file types, such as TIFF format images.

JPEG/JFIF is the format most used for storing and transmitting photographs on the World Wide Web. For this application, it is preferred to formats such as GIF, which has a limit of 256 distinct colors that is insufficient for color photographs, and PNG, which produces much larger image files for this type of image. The compression algorithm is not as well suited for line drawings and other textual or iconic graphics, and thus the PNG and GIF formats are preferred for these types of images.

The MIME media type for JPEG is image/jpeg (defined in RFC 1341).