Which version of Mac OS X first included the Mac App Store?

Mac OS X Snow Leopard, specifically version 10.6.6, first included the Mac App Store.

Snow Leopard originally launched on August 28, 2009, as Mac OS X 10.6. The Mac App Store arrived later through the free 10.6.6 update, released on January 6, 2011. Therefore, the stored answer identifies the correct operating-system version, even though the precise update number is 10.6.6.

Apple announced the service at its October 2010 “Back to the Mac” event. It brought an App Store-style digital marketplace to the Mac, allowing users to discover, purchase, download, and update software from one place. The model followed the success of Apple’s iPhone and iPad App Store.

A frequent confusion involves OS X Lion, which was distributed primarily through the Mac App Store from its release in July 2011. Lion did not introduce the Mac App Store; it was the first major Mac operating-system release distributed through it.