The MIME type image/jpg is used to denote the presence of images compressed and stored in the JPEG format. This MIME type is classified under the "image" category.

The JPEG format carries the extension JPEG or JPG. It is a very popular format for compressing and storing images. The format is named after the group that created the standard � Joint Photographic Experts Group. JPEG is an adjustable format where the degree of compression can be adjusted to balance the quality loss and resulting file size. The standard is so very popular because it can typically achieve 10:1 compression ratios without perceptible drops in the quality. It is a format that is widely used for transmitting photographic images over private networks as well as the World Wide Web. Although there are variations in the format, they are all uniformly known as JPEG. The interlaced progressive JPEG format is especially useful for large images that will be used over the Internet.

The JPEG group was formed in the year 1986 and the format was released in the year 1992. In 1994, the International Standards Organization (ISO) approved the format and standardized it as ISO 10918-1. The JPEG format standard defines both the compression process and decompression process, thereby acting as a CODEC.