Fedora 21 is now available to the general public, representing the first OS release to come out of the Fedora.next initiative, which emphasizes increased modularity and flexibility that go beyond the desktop. It's a new vision for Fedora, in terms of the way it's developed and the types of users it's targeting, and with Fedora 21 come three different variants -- Fedora 21 Cloud, Fedora 21 Server, and Fedora 21 Workstation.
