A platform originally created and only produced by Commodore, but now owned by Gateway 2000 and produced by it and a few smaller companies. It was historically the first multimedia machine and gave the world of computing many innovations. It is now primarily used for audio / video applications; in fact, a decent Amiga system is less expensive than a less capable video editing system. Many music videos were created on Amigas, and a few television series and movies had their special effects generated on Amigas. Also, Amigas can be readily synchronized with video cameras, so typically when a computer screen appears on television or in a movie and it is not flickering wildly, it is probably an Amiga in disguise. Furthermore, many coin-operated arcade games are really Amigas packaged in stand-up boxes. Amigas have AmigaOS for their OS. New Amigas have either a PowerPC or an Alpha for their main processor and a 68xx processor dedicated to graphics manipulation. Older (and low end) Amigas do everything with just a 68xx processor.
The last home computer in the world, before the world went PC and/or see-thru plastic rubbish insane. This statement is probably more controversial due to the fact the Amiga was created by Commodore (before they went and lost the plot slightly and ended up selling the rights to other companies). It's the computer I use to do all of the hacking for, and the writing of, this very WWW page ( ZXAM for hacking, ASp for 128K testing/saving as 48K for ZXAM, PPaint/ADPro for the graphics, and Cygnus Editor for the actual WWW pages)
Acronym for "Amazing Machine Intended for Graphics Artists".