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
Windows Mobile Windows Mobile's share of the smartphone market grew from its inception while new devices were being released. After peaking in 2007, it saw decline year-on-year. In Q1 2003, Windows Mobile was the third largest operating system in the smart handheld market, behind Symbian and Palm OS. In Q1 2004, Windows Mobile accounted for 23% of worldwide smartphone sales. Windows Mobile was projected in 2005 to overtake Symbian to become the leading mobile OS by 2010. In Q3 2004, Windows Mobile (CE) surpassed Palm OS to become the largest PDA operating system. In Q4 2005 Microsoft shipped 2.2 million PDAs, which