OS X

OS X (pronounced /oʊˌɛsˈtɛn/, oh-ess-TEN; originally Mac OS X) is a series of Unix-based graphical interface operating systems (OS) developed and marketed by Apple Inc. It is designed to run on Macintosh computers, having been pre-installed on all Macs since 2002. OS X is the fourth most popular general purpose OS; within the market of desktop, laptop and home computers, and by web usage, OS X is the second most widely used desktop OS after Windows.

OS X was the successor to Mac OS 9, released in 1999, the final release of the "classic" Mac OS, which had been Apple's primary operating system since 1984. The first version released was Mac OS X Server 1.0 in 1999; a desktop version, Mac OS X v10.0 "Cheetah" followed on March 24, 2001. All consumer releases of OS X up to 2013 were named after big cats; for example, OS X v10.8 was referred to as "Mountain Lion". However, with the announcement of OS X Mavericks in June 2013, this was dropped in favor of Californian landmarks.

OS X, whose X is the Roman numeral for 10 and is a prominent part of its brand identity, is built on technologies developed at NeXT between the second half of the 1980s and Apple's purchase of the company in late 1996. The 'X' is also used to emphasize the relatedness between OS X and UNIX. UNIX 03 certification has been achieved for versions 10.5 for Intel CPUs, and versions 10.6 through 10.11.iOS, the mobile OS for the iPhone, iPod Touch,iPad, and the 2nd and 3rd generation Apple TV, shares the Unix-based core and many frameworks with OS X. An unnamed variant of v10.4 powers the first generation Apple TV. Apple also formerly issued a separate line of editions for server use.

OS X El Capitan

OS X El Capitan (el-KAP-ɪ-TAN) (version 10.11) 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. There were multiple betas released after the keynote. OS X El Capitan was released to end users on September 30, 2015, as a free upgrade through the Mac App Store.

System requirements

All Macintosh computers that can run OS X Mavericks or Yosemite can run El Capitan, although not all of its features will work on older computers. For example, Apple notes that newly available Metal API is available on "all Macs since 2012".

El Capitan

El Capitan (Spanish for The Captain, The Chief) is a vertical rock formation in Yosemite National Park, located on the north side of Yosemite Valley, near its western end. The granite monolith extends about 3,000 feet (900 m) from base to summit along its tallest face and is one of the world's favorite challenges for rock climbers and BASE jumpers.

The formation was named "El Capitan" by the Mariposa Battalion when it explored the valley in 1851. El Capitan ("the captain", "the chief") was taken to be a loose Spanish translation of the local Native American name for the cliff, variously transcribed as "To-to-kon oo-lah" or "To-tock-ah-noo-lah". It is unclear if the Native American name referred to a specific tribal chief or simply meant "the chief" or "rock chief". In modern times, the formation's name is often contracted to "El Cap", especially among rock climbers and BASE jumpers.

The top of El Capitan can be reached by hiking out of Yosemite Valley on the trail next to Yosemite Falls, then proceeding west. For climbers, the challenge is to climb up the sheer granite face; there are many named climbing routes, all of them arduous. Some of these include the iron hawk route, the sea of dreams route, etc.