The Groovy Version Scheme
Since Groovy 2.0.0:
Since Groovy 2.0.0 we follow the scheme as described in http://semver.org/. This means the next minor version after 2.0.0 is 2.1.0, the first bugfix version after 2.0 is 2.0.1 and the next major version will be 3.0.0.
Before Groovy 2.0.0:
Before Groovy 2.0.0 we followed a version scheme where we have X.Y.Z, where X.Y is the major version, and Z the minor version. Bugfix versions where not really done, you had to upgrade to the next minor version for that. Since Groovy 1.0 we incremented only the Y for a new major version. The increment of X we wanted to leave for a very big breaking change, like a new MOP. The last major version in these scheme is 1.8(.0), 1.8.1 is the first minor and bugfix version. The major versions in the past using this scheme are: 1.8, 1.7, 1.6, 1.5, 1.0. Each of them having around 10 minor/bugfix versions.