The GIF format was developed in 1987 by CompuServe Incorporated, primarily for use on the Internet. The current version, GIF89a, was released in 1990. It supports colour depths from 1-bit (monochrome) to 8-bit (256 colours) and always stores images in compressed form, using lossless LZW compression. Other supported features include interlacing and transparency.
GIF is a proprietary format. In addition, the patent for the LZW algorithm is owned by Unisys Corporation, which has licensed its use by CompuServe. Despite the controversy that surrounded the application of license fees to GIF readers and writers and the developments of alternative open formats such as PNG the GIF format remains one of the most widespread in use, particularly on the Internet. The US patent expired in June 2003 and the UK patent expired in June 2004.