Agreeing to incremental launch stages and the criteria that govern promotion from one stage to the next makes launch commitments, aka deadlines, less risky. For example, Google SRE’s launch plan documentation describes four: Early Access Preview, Alpha, Beta and General Availability (GA). Committing to a GA launch is easier after a successful Beta, which is easier after a successful Alpha, end so on.
Comparable to a deployment pipeline, promotion from one stage to the next ideally concerns stability rather than features. In other words, if the difference between Alpha and Beta is a length of time without issues, we can promote with confidence after that time, but if the difference is a set of new features, we don’t know how those features will perform.