Release notes and general information about GameMaker releases.
Released roughly every other month. Fairly stable, but may have the odd lower-severity issue.
Long Term Stable means very few new features are ever added and it only gets critical bug fixes each time there is an (infrequent) update.
Most up-to-date version and released frequently, so you can get the newest features and fixes ASAP - but accordingly these releases will contain bugs, so please do report any you find!