Seven years after introducing the GIF format, during which it became a defacto standard because of its efficient compression algorithm, Compuserve reaches a licensing agreement with Unisys over the use of the patented LZW method in the GIF specification. CompuServe was not aware of the patent when it used the LZW technique in 1987 and Unisys was not aware that LZW was used in the GIF format until 1993. By the time the settlement was reached, the use of the GIF format had become widespread on the early world wide web. During the announcement of the licensing agreement with Compuserve, Unisys made it known that they expected all commercial services or software that used the GIF format or the LZW method to pay licensing fees. While the arrangement would likely not have affected anyone who used GIF graphics on their web sites, the announcement was generally met with outrage. Many people and organizations criticized Unisys for attempting to collect licensing fees on a format that was commonly considered to be freely available. The most famous condemnation was the “Burn All GIFs” campaign by the League for Programming Freedom. The uproar over the GIF licensing arrangement led to the development of the patent-free PNG format. The LZW patent expired worldwide during 2003 and 2004 so the GIF file format is now completely free to use.