An edit-a-thon is an event where some editors of online communities such as Wikipedia, OpenStreetMap, and LocalWiki edit and improve a specific topic or type of content. The events typically include basic editing training for new editors and may be combined with a more general social meetup. The word is a portmanteau of "edit" and "marathon". An edit-a-thon can either be "in-person" or online or a blended version of both. If it is not in-person, it is usually called a "virtual edit-a-thon" or "online edit-a-thon".

Wikipedia is a free content online encyclopedia written and maintained by a community of volunteers, known as Wikipedians, through open collaboration and the use of the wiki-based editing system MediaWiki. Wikipedia is the largest and most-read reference work in history. It is consistently ranked as one of the ten most popular websites in the world, and as of 2024 is ranked the fifth most visited website on the Internet by Semrush, and second by Ahrefs. Founded by Jimmy Wales and Larry Sanger on January 15, 2001, Wikipedia is hosted by the Wikimedia Foundation, an American nonprofit organization that employs a staff of over 700 people.