As a general concept which many developers follow when writing complex software, is to regularly make available "Snapshot" releases to all the testers. Snapshot builds are generated right before moving forward with another large change. They allow the testers to evaluate features. and review the software as it is being developed.
As a general source control (version control) term, a snapshot version indicates a view of the source code taken at a specific time. This is not necessarily stable or ready for full use and can be changed in the future, as opposed to a release version which is stable and should be final and ready for a general release.
Snapshots are also used where if a bug gets introduced in development, we can go backwards a few snapshot steps to see where that bug started, and then easily handle it.