Apple Mac OS X is the operating system for Apple Macintosh computers on the PowerPC (PPC) and Intel x86 platform. The latest version of OS X is Snow Leopard, Build 10D571
Apple released to the public, on September 13, 2000, a "preview" version of Mac OS X (internally codenamed Kodiak) in order to gain feedback from users, which cost $29.95. The "PB" as it was known marked the first public availability of the Aqua interface and Apple made many changes to the UI based on customer feedback. Mac OS X Public Beta expired and ceased to function in Spring 2001
This version of Mac OS X introduced Spotlight, the first search that can integrate into most apps.
This version of Mac OS X introduces 2 new mac features: Time Machine, to find and restore your backups when you need them, or if you just accidentaly deleted a file, and Spaces, Moving your windows into 4 personalizable spaces.
Snow Leopard (10.6)
A preview of Lion was publicly unveiled at Apple's "Back to the Mac" event on October 20, 2010. It will bring many developments made in Apple's iOS, such as an easily-navigable display of installed applications, to the Mac, and will include support for the Mac App Store, as introduced in Mac OS X Snow Leopard version 10.6.6. On February 24, 2011, the first developer's preview of Lion (11A390) was released to subscribers of Apple's developers program. The latest preview (build 11A459e) was released on May 13, 2011.
In a press release by Apple on May 31st, 2011, an announcement was made that this new release will be unveiled by Steve Jobs on June 6th at the WWDC 2011.
It was scheduled to release on Summer 2011.
This was also the last Mac OS developed before Steve Jobs died.
Mountain Lion (10.8)
Currently in development