A large, once respected IT consulting company who nowadays seem to dwindle into irrelevance. Apparently they mostly recommend MicrosoftWindows solutions. They earned a huge notoriety with the computing world with their Submarine Patent on LZW compression. This patent is no longer an issue - it expired on Fri, Jun 20 2003 (in the United States... other countries may have different patent time limits and/or separately filed patents).
In 1984, Terry Welch, working at Unisys, extended the LZ78 algorithm with a few simple ideas to make it simpler and more efficient. Following standard procedures, a patent was filed on this new Algorithm dubbed LZW. However, Unisys didn't have much interest in it as it wasn't of any use to their core business. They assured anyone who asked that they allowed free use of the Algorithm. Fatally, none of this was ever formally put in contract.
The patent was almost forgotten by the time CompuServe were looking to make moving images across the typical 14k4 MoDem connections of the days easier. They decided to use the simple, elegant, and efficient LZW compression in a new FileFormat for images which they dubbed GIF. The format gained popularity quickly and became the defacto standard for publishing images online. It tagged along when the InterNet became big, and hung around for the era of the WorldWideWeb. Every other image on the web and then some was a GIF image.
Eventually, Unisys woke up to the fact a lot of people had become dependent on LZW. They realized that their patent could make them a substantial amount of money from license fees if they asserted their ownership. Everyone was using it and noone could avoid doing so. This was too tempting; Unisys decided to break the surface and proceeded to make a huge amount of noise about their patent.
Their hypocrisy led to the creation of the PNG FileFormat to fill the niche GIF traditionally held, including a lot of features GIF had been missing. PNG is now preferred over GIF. However, Unisys have made a lasting impression on the computing world that goes far beyond image formats. People have become very careful to examine whether anything proposed as a new standard is covered by existing patents. OggVorbis is an example of another format that was designed specifically to avoid patented algorithms.