OS X Yosemite (version 10.10) is the eighth important version of OS X. OS X is Apple's computer operating system. It was announced at Apple's Worldwide Developers Conference (WWDC) 2014 on June 2, 2014. It was released to developers and beta testers on that same day. It was released to everyone on October 16, 2014. OS X Yosemite is named after Yosemite National Park in California.