IRIX (/ˈaɪrɪks/, EYE-ricks) is a discontinued operating system developed by Silicon Graphics (SGI) to run on the company's proprietary MIPS workstations and servers.

In IRIX, SGI originated the XFS file system and the industry-standard OpenGL graphics API.

An overlay upgrade from 6.5.x to the 6.5.22 maintenance release was available as a free download, whereas versions 6.5.23 and higher required an active Silicon Graphics support contract.

[11] On September 6, 2006, an SGI press release announced the end of the MIPS and IRIX product lines.

[13] Much of IRIX's core technology has been open sourced and ported by SGI to Linux,[14][15][16][17][18] including XFS.

[5] In the early 1990s, IRIX was a leader in Symmetric Multi-Processing (SMP), scalable from 1 to more than 1,024 processors with a single system image.

IRIX was widely used for the 1990s and 2000s in the computer animation and scientific visualization industries, due to its large application base and high performance.

IRIX is one of the first Unix versions to feature a graphical user interface for the main desktop environment.

[32] IRIX is the originator of the industry standard OpenGL for graphics chips and image processing libraries.

[32][38][39] 4Dwm on IRIX was one of the first default graphical user interface desktops to be standard on a Unix computer system.