Apple's Mountain Lion, also known as OS X 10.8, is likely to be retired from support this fall as Apple launches its newest OS, El Capitan.\n\n\nIf Apple continues its previous practice, users of Mountain Lion can expect to receive the OS's final security update in mid-September, a month before the expected launch of El Capitan.\n\n\nMountain Lion, the last of the cat-named systems, debuted in July 2012, and Apple charged users $19.99 for the update. Apple dropped that practice after Mountain Lion and now issues its newest OS for free.\n\n\nApple appears to provide support for three OSes at a time, and the arrival of El Capitan, presumably in October, will push Mountain Lion into retirement. The other two supported systems are Maverick (OS X 10.9) and Yosemite (OS X 10.10).\n\n\nUnlike other software vendors, Apple doesn't reveal its support policies, so there's no guarantee on Mountain Lion's support retirement. Based on previous Apple practices, here are some of the reasons it's likely:\n\n\nApple last year served the final security updates to Lion, OS X 10.7, which was the predecessor to Mountain Lion, in September;\nIn 2013, Apple released its final security update for Snow Leopard, OS X 10.6, in September;\nMountain Lion's user share by the end of September is expected to be less than 5%, half of what Lion had when it was retired. According to Web analytics vendor Net Applications., 60% of Macs run the Yosemite OS, and 20% are on 2013's Mavericks.\nUsers of Mountain Lion will be able to migrate to El Capitan, which is a free upgrade.\n\n\nMeanwhile, users running Yosemite can expect in September to receive that OS's final non-security update, which fixes bugs, improves reliability and performance, and possible includes new features, just as the plug is pulled on Mountain Lion.\n\n\nWith reports by Gregg Keizer at Computerworld.