This is the most popular multi-user Operating System in use today. It was originally developed at AT&T Bell Labs. Similar (but not completely compatible) versions have been developed by universities, volunteers, corporations and vendors of high-end computing hardware.
Popular variants, or flavours of Unix in use today include:
- Solaris, from Sun Microsystems.
- AIX, from International Business Machines (IBM).
- Digital Unix, from Compaq (which purchased Digital Equipment).
- IRIX, from Silicon Graphics (SGI)
- HPUX, from Hewlett-Packard.
- SCO, from the Santa Cruz Operation.
- FreeBSD, maintained by a group of individuals.
- OpenBSD, maintained by a group of individuals with a single coordinator.
- NetBSD, maintained by a Foundation incorporated in the state of Delaware.
- Linux, maintained by a loosely coordinated group of volunteers.