Hacktoberfest is a month-long celebration from October 1-31 run by DigitalOcean, GitHub, and Twilio to encourage contributions to open source software projects. Participants can earn rewards by making 4 quality pull requests to any GitHub repository in October. Open source software is software that is freely available to use, redistribute, and modify through a transparent peer review process. Major open source events help promote open source software and hardware. Both free and open source options exist as alternatives to proprietary software.