Mac OS X Lion

Mac OS X Lion is an operating system. It is the eighth major release of Apple's Mac OS X software line. It is made for Macintosh desktops, laptops, and servers. It was released on 20th July 2011 via the Mac App Store.
Lion was unveiled to the public at Apple's "Back to the Mac" event on October 20, 2010. It brings developments from iOS (Apple's mobile operating system for the iPhone, iPod Touch, and iPad), such as the App Store, to the Mac. 
New or changed features.
Some new features were announced at the "Back to the Mac" keynote, however more features are expected to be revealed closer to the release date.