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.
OS X El Capitan includes features to improve the security, performance, design and usability of OS X. Compared to OS X Yosemite, Apple says that opening PDFs is four times faster, app switching and viewing messages in Mail is twice as fast, and launching apps is 40% faster. The maximum VRAM allocation has been increased from 1024 MB to 1536 MB on Macs with an Intel HD 4000 GPU. OS X El Capitan supports Metal, Apple's graphics API introduced in iOS 8 to speed up performance in games and professional applications. San Francisco replaces Helvetica Neue as the system typeface of OS X El Capitan. OS X El Capitan now uses LibreSSL as opposed to the arguably less secure OpenSSL used in prior OS X versions.
Mac App Store: https://itunes.apple.com/us/app/os-x-el-capitan/id1018109117?mt=12