Android (operating system) store, and by September 2013, one billion Android devices have been activated. , the Google Play store has over 2.7 million Android applications published, and , apps have been downloaded more than 65 billion times. The operating system's success has made it a target for patent litigation as part of the so-called "smartphone wars" between technology companies. Android devices account for more than half of smartphone sales in most markets, including the US, while "only in Japan was Apple on top" (September–November 2013 numbers). At the end of 2013, over 1.5 billion Android smartphones have been sold in the four
Usage share of operating systems down to 72.76% and Chrome OS at 3.33%, plus traditional Linux at 1.46%. There is little openly published information on the device shipments of desktop and laptop computers. Gartner publishes estimates, but the way the estimates are calculated is not openly published. Another source of market share of various operating systems is StatCounter basing its estimate on web use (although this may not be very accurate). Also, sales may overstate usage. Most computers are sold with a pre-installed operating system (OS); some users replace that OS with a different one due to personal preference, or install another OS alongside it