Mac OS X Snow Leopard (version 10.6) is the seventh major release of Mac OS X, Apple's desktop and server operating system forMacintosh computers. Snow Leopard was publicly unveiled on June 8, 2009 at the Apple Worldwide Developers Conference. On August 28, 2009, it was released worldwide, and was made available for purchase from Apple's website and its retail stores at the price of US$29 for a single-user license. As a result of the low price, initial sales of Snow Leopard were significantly higher than that of its predecessors. The release of Snow Leopard came nearly two years after the introduction of Mac OS X Leopard, the second longest time span between successive Mac OS X releases (the time span between Tiger and Leopard was the longest).