The Solaris Operating System, usually known simply as Solaris, is a Unix-based operating system introduced by Sun Microsystems in 1992 as the successor to SunOS.

Solaris is known for its scalability, especially on SPARC systems, as well for being the origin for many innovative features such as DTrace and ZFS. Solaris supports SPARC-based and x86-based workstations and servers from Sun and other vendors, with efforts underway to port to additional platforms.

Solaris is certified against the Single Unix Specification. Although it was historically developed as proprietary software, a majority of its codebase is now open source software.

Source: Wikipedia