Google's Android Open Source Project (AOSP) rolled out in 2007 with the goal of creating a unified framework for mobile operating systems and, in turn, expediting the development of mobile products. The core of the code was open to everyone, but to help guarantee quality products -- and promote its own services in the face of Apple's iOS -- Google also organized the Open Handset Alliance (OHA). Companies who pledged allegiance to this group effectively committed to certain standards of quality for any resultant Android hardware and software. Membership in the OHA, however, is not a requirement for AOSP and so numerous forked (read: compatible and non-compatible) versions, like Amazon's Fire OS, have been developed over the years. We've pinpointed just a few of these to highlight the vibrant -- and often political -- undercurrent of Android's alternate identities.
You take the good, you take the bad, you take them both and there you have: the forks of Android life.