1. Someone gets an idea for a site, and proposes it on Area 51.
2. A bunch of other people like the idea, so they commit on Area 51 to contributing to the site should it get launched.
3. Some sample questions are created on Area 51, and discussions are held to define the scope.
4. A private beta is launched, usually lasting a few weeks, with just the users who committed on Area 51.
5. A public beta is launched, usually lasting ---5 years--- a few months, where anybody can join the site. Shortly afterwards, pro-tem moderators are appointed.