Hacktoberfest, organized by DigitalOcean and hosted on GitHub, is a month-long celebration of open source coding held every October, where participants can contribute to any open source project by submitting pull requests. Participants can engage by fixing bugs, adding new features, or improving documentation, and are encouraged to share their contributions using the #hacktoberfest hashtag. Each day of the event, a different open source project seeking contributors is featured on the Hacktoberfest website to inspire participation. To receive a free, limited edition Hacktoberfest t-shirt, participants must sign up on the Hacktoberfest website and successfully submit at least four pull requests by the end of October, after which DigitalOcean will collect shipping details to distribute the shirts.