The basics:

All pull/merge requests must be submitted to opted-in, public repositories between October 1 and October 31, 2023. The first 50,000 participants who have their first pull/merge request accepted will have a tree planted, and everyone who completes Hacktoberfest with all four pull/merge requests accepted will unlock the virtual swag kit. Avoid submitting low-quality pull/merge requests. Please refer to our values, spam guidelines, and pull/merge request details to better understand how we validate contributor requests. Project maintainers must accept your pull/merge requests for them to count towards your total. Any contributor with 2+ spammy requests will be automatically disqualified. Repositories on GitHub and/or GitLab that go against Hacktoberfest's values will be excluded from qualification, and pull/merge requests made to those projects will be excluded. Please only submit pull/merge requests to repositories with the hacktoberfest topic. Found a repository that goes against Hacktoberfest's values? Let us know, and we'll take a look!

There’s plenty more in store, so be sure to check out the Hacktoberfest website for all the ways you can get involved this year.