OS X version 10.11, also known as "El Capitan" (el-kap-ɪ-tan), is the twelfth major release of OS X, Apple Inc.'s desktop and server operating system for Macintosh computers. It is the successor to OS X Yosemite and focuses mainly on performance, stability and security. Following the California landmark-based naming scheme introduced with OS X Mavericks, El Capitan was named after a rock formation in Yosemite National Park.
The first beta of OS X El Capitan was released to developers shortly following the 2015 WWDC keynote on June 8, 2015. The first public beta was made available on July 9, 2015. OS X El Capitan was officially launched on September 30, 2015, as a free upgrade through the Mac App Store.