This breaks down into the following elements:
2020- The year of the release.
1- The minor release number within the year, starting at one.
0- The patch number for the update, starting at zero which means no patch.
rc1- The release stage suffix, in this case denoting that this is "release candidate number one".
Each beta that follows a stable release will increment either the year or the minor release number, depending on whether the beta falls in or close to a new calendar year or not.
Patch numbers only increase after a release is marked
-stable. Prior to that, the beta or release candidate number is denoted after the release stage suffix, e.g.,
Valid suffixes include
-stable, although in practice alpha releases are internal only.
Here are a series of examples as the version numbers increment with new updates: