The software can be downloaded through the software update function of the Mac App Store.
A new public beta version of Yosemite and Yosemite Developer Preview 8 were released last week, on Monday. The software is expected to continue on in its beta testing phase until late October, when it will be released to the public.
OS X Yosemite brings several new features to the operating system, including Continuity, which offers unprecedented integration between iOS and OS X. The operating system also includes a complete visual overhaul with a flatter iOS 7-style look.