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 Smartphone Mobile Smartphones were introduced with the Pocket PC 2002 operating system for Pocket PCs. Although in the broad sense of the term "Smartphone", both Pocket PC phones and Microsoft branded Smartphones each fit into this category, Microsoft's use of the term "Smartphone" includes only more specific hardware devices that differ from Pocket PC phones. Such Smartphones were originally designed without touchscreens, intended to be operated more efficiently with only one hand, and typically had lower display resolutions than Pocket PCs. Microsoft's focus for the Smartphone platform was to create a device that functioned well as a phone and data device