Version
A version is a revision of the original content item that remains associated with the original. Using versions you can track changes to a content item. You also have the ability to restore the content item to a specific version.
In the following example, Version 1 is the original version and each new version is a revision of that first version.

Version 5 is the current version. In other words, it is currently the master version. You can change the current version to another version by clicking Restore.
If you restore Version 1, a copy of Version 1 is created and becomes the current version (Version 6).

With content versioning, you can:
The frequently asked questions topic explains the difference between versions, drafts, and variants.