Understanding GIMP version numbers
Even numbers (2.8, 2.10, …) are stable versions, that are intended for allday use. Odd versions (2.7, 2.9, …) are development versions that are usually not available as package/binary executable. To use them, you have to compile them yourself.
Since GIMP 2.8 the developers introduced a change in the versioning system. From now on odd sub numbers (micro version numbering) in the stable branch are working draft versions where the work of bugfixing is being done. I.e. 2.8.3 will never be released as a stable version although 2.8.x is indicating a stable branch. Instead the next stable version will be a 2.8.4. Same is for the unstable branches which are marked with odd numbers like 2.9 in general. Here the micro numbers (i.e. 2.9.1) indicates that this is a working copy. Even micro numbers like 2.9.2 could be released as tarballs, that you can download. So you’ll never see a tarball released with a odd micro number in the development branch (aka as the master branch).
To get pre-compiled versions or the source code of GIMP, see our download page.
Current GIMP versions
You can get the current code base via git. It is also available for browsing in the Web.
This is the current stable (= for production use) version of GIMP.
New features in GIMP 2.6 (in comparison to GIMP 2.4)
New features in GIMP 2.4 (in comparison to GIMP 2.2)