GIF images are compressed with Lempel-Ziv-Welch`s (LZW) loss-free data compression technique to reduce file size without compromising visual quality. This compression technique was patented in 1985. The controversy over the licensing agreement between Unisys and CompuServe, the software patent holder, in 1994, spurred the development of the PNG (Portable Network Graphics) standard. Until 2004, all relevant patents had expired. The popularity of LZW led CompuServe to choose it as a compression technique for its version of GIF, which was developed in 1987. CompuServe was not aware of the patent at the time.  Unisys learned that the GIF version used the LZW compression technique and began licensing negotiations with CompuServe in January 1993. The agreement that followed was announced on 24 December 1994.  Unisys stated that they expected that all major commercial online information services companies that use the LZW patent would license Unisys technology at a reasonable price, but that they do not require licensing or royalties for non-commercial and for-profit gif applications, including those intended to be marketed online.
 In June 1984, an article by Welch appeared in IEEE magazine, which for the first time publicly described the LZW technique.  LZW became a popular data compression technique, and when the patent was issued, Unisys entered into licensing agreements with more than a hundred companies.   Differences of opinion on the debate have given rise to a lively debate on the Internet. At the award for the work of his life at the 2013 Webby Award, Wilhite rejected the “G” debate and his speech resulted in 17,000 Articles on Twitter and 50 News Articles.  The White House and the television show Jeopardy! 2013 entered the debate.  In 2006, Mozilla proposed an extension of the PNG aPNG (Animated Portable Network Graphics) format as an alternative to the MNG format. APNG will be supported by most browsers from 2019.  APNG animates PNG files, while top-down compatibility is maintained in set-top boxes that cannot understand the animation block (unlike the MNG). Older set-top boxes easily makes the first frame of animation. On April 20, 2007, the PNG Group officially rejected the apng as an official extension.
 There have been several subsequent suggestions for a simple animated graphic format, based on PNG and using different approaches.  However, Animated Portable Network Graphics is still developed by Mozilla and supported in Firefox 3 while MNG support has been removed.   APNG is currently supported by all current web browsers, including Chrome from version 59.0 and Opera and Firefox and Edge.