We originally envisaged an alternating between so-called "stable" releases (intended for production deployment) and intermediate "snapshot" releases (to bring new developments to users in a faster way). However, since these "snapshot" releases were already heavily tested and vetted to provide the same level of stability as any other release, this distinction quickly became meaningless and was therefore dropped.
The old notation of a "snapshot" release still persists, but as a user you can think of each just as a normal release (with it being identified through a date string YYYYMMDD, like "20210224").
