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),
Distributed operating system and functionality required of an OS but adds attributes and particular configurations to allow it to support additional requirements such as increased scale and availability. To a user, a distributed OS works in a manner similar to a single-node, monolithic operating system. That is, although it consists of multiple nodes, it appears to users and applications as a single-node. Separating minimal system-level functionality from additional user-level modular services provides a “separation of mechanism and policy.” Mechanism and policy can be simply interpreted as "what something is done" versus "how something is done," respectively. This separation increases flexibility and scalability. At