Deflate

In computing, Deflate (stylized as DEFLATE, and also called Flate) is a lossless data compression file format that uses a combination of LZ77 and Huffman coding. It was designed by Phil Katz, for version 2 of his PKZIP archiving tool. Deflate was later specified in Request for Comments (RFC) 1951 (1996).

Katz also designed the original algorithm used to construct Deflate streams. This algorithm received software patent U.S. patent 5,051,745, assigned to PKWare, Inc. As stated in the RFC document, an algorithm producing Deflate files was widely thought to be implementable in a manner not covered by patents. This led to its widespread use. For example, in gzip compressed files and Portable Network Graphics (PNG) image files, in addition to the ZIP file format for which Katz originally designed it. The patent has since expired.