International Fanworks Day is observed worldwide every February 15 to celebrate and promote various forms of fanworks, including fan fiction, fan art, fan videos, and cosplay. The day was established by the Organization for Transformative Works (OTW) after reaching significant milestones with its projects, Archive of Our Own (AO3) and Fanlore, in 2014. Since its inception in 2015, the day has encouraged fan content creators and enthusiasts to engage in activities such as fanwork challenges, public discussions, and feedback fests. Participants may also choose to create new fanworks, recommend favorites, or contribute to the OTW through donations or volunteering. The celebration highlights the creativity of fans and the diverse formats of transformative works, while also acknowledging the legal nuances surrounding fan creations under U.S. copyright law.