Android (operating system) and rival Linux mobile operating systems that were in development. These established players were skeptical: Nokia was quoted as saying "we don't see this as a threat," and a member of Microsoft's Windows Mobile team stated "I don't understand the impact that they are going to have." Since then Android has grown to become the most widely used smartphone operating system and "one of the fastest mobile experiences available". Reviewers have highlighted the open-source nature of the operating system as one of its defining strengths, allowing companies such as Nokia (Nokia X family), Amazon (Kindle Fire), Barnes & Noble (Nook),
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