JPEG
From Just Solve the File Format Problem
JPEG, named after the Joint Photographic Experts Group, which created the format, is a lossy compressed format well-suited to photographic images. Line drawings do better with non-lossy compressed bitmaps such as GIF and PNG.
The JFIF (JPEG File Interchange Format) further specifies the particular subset of the JPEG standard intended to be used for standardized image files, skipping some of the advanced features of JPEG intended for specific application use.