OS X Yosemite
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Yosemite is the current version of OS X, released on October 16, 2014. It was announced at the 2014 WWDC, and is currently available for free download from the Mac App Store for all users. Yosemite is perhaps the largest change to Mac OS since the release of 10.0 itself, with a completely redesigned Aqua UI inspired by the translucent "Glass" design of iOS 7, new icons, Continuity, Spotlight 2, and other large-scale changes.