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
Market share share is closely monitored for signs of change in the competitive landscape, and it frequently drives strategic or tactical action." Increasing market share is one of the most important objectives of business. The main advantage of using market share as a measure of business performance is that it is less dependent upon macro environmental variables such as the state of the economy or changes in tax policy. In the United States market, however, increasing market share may be dangerous for makers of fungible and potentially hazardous products such as medicine, due to a US-only legal doctrine called market share liability.