To support open-source contribution a program "HactoberFest" is held by DEV and Digital Ocean in collaboration with Github every year.
GitHub is a version control platform where you can share your projects and can also contribute to other projects, for that you have to open a pull request.
HactoberFest is an event based on opening 4 pull request to encourage open source contribution. And as an award by DEV and Digital Ocean swags are given to them. These swags includes tree/t-shirt, stickers and badges.
To participate, register at the official site: hacktoberfest.digitalocean.com Make sure you are connected with your GitHub account. Then, submit at least four pull-request (PRs) to any public GitHub repository.