UNIX is the trademarked form of Unics (Uniplexed Information and Computing System). UNIX is an important Operating System developed in 1969 by AT &T. Dennis Ritchie and Ken Thompson were the brains behind this OS.
Though the name UNIX is trademarked , UNIX is more like a family name now, which is not used for a single product but is common for different variants having acceptable UNIX characteristics.
Important commercial versions of UNIX include :
Solaris – Owned by Sun
HP-UX- Owned by HP
AIX – Owned by IBM
Linux is a similar kind of OS like UNIX, has similar kind of characteristics , but can be classified as a separate OS. Linux is a free software and is now associated with Free Software Foundation.(Previously known as GNU-GNU is NOT UNIX)