A JFIF file is an image file format that uses JPEG compression. It is a variation of the common .JPEG file format, designed to include a minimal amount of data and allow easy exchange across multiple platforms and applications. JFIF builds over the JPEG Interchange Format (JIF) to solve some of JIFs limitations, including unnecessary complexity, component sample registration, resolution, aspect ratio, and color space. A JFIF file consists of a sequence of markers or marker segments, as defined in part 1 of the JPEG Standard. Each marker consists of two bytes (FF followed by a byte that specifies the type of marker) . Markers can either be stand-alone or indicate the start of a marker segment. JFIF allows multiple components like Y, Cb, Cr, to have different color interpretations.

JFIF files can be opened using a variety of Windows and macOS programs, including the Photos and Preview apps bundled with the operating systems. To open a JFIF file in Preview, you may have to drag the file into Preview, rather than attempting to open it through Finder. JFIF files can also be converted to JPG using third-party conversion methods or free online file converters.