OS X El Capitan

OS X El Capitan (10.11.x) is the twelfth major release of the Mac OS X operating system released in 2015 by Apple. It is the last version of Mac OS X to have support for non-SSE4 Intel CPUs (like the 65nm Core 2 Duo (Merom) and the 65nm Xeon (Clovertown).

Features

 * New window management features were introduced.
 * Enhanced multi-touch gestures for Mail, Messages, etc.
 * Notes app received a complete overhaul.
 * Major improvements to Safari.
 * System Integrity Protection (SIP) is a new security mechanism.