It is called Yosemit OS X and here is a video that presents an introduction to the new operating system upgrade from Apple:
From 24 July 2014 onwards, the company will be officially opening of the beta program so the users can test them. 1 million people are being offered the free operating system ahead of its official release this fall.
Its offering the free beta version to so many people because this time Apple isn’t just seeking feedback from developers and techie people, the company also wants to get some feedback from general users. The non-techie Mac users often spot bugs that developers don’t. The company also feels encouraged by the fact that 55% of the current Mac owners have upgraded to Mavericks, which is its latest release, making it by far the fastest Mac OS adoption compared to any other previous version. Here is a small review of Yosemite OS X on the Mashable website.