There are few technological developments that had more of a visible impact on participatory culture in the 2000s than the wiki. Although the software was designed for small-scale and local uses, wikis have emerged as a major tool used by internet users on a daily basis. From the world’s most popular encyclopedia, Wikipedia, to hundreds of specialized sites serving a vast array of subcultures and groups, wikis have become one of the hallmark tools of the participatory internet, or Web 2.0. This article will outline the development of wikis as a software platform and the cultural rise of Wikipedia before considering a range of participatory practices tied to one of the most widespread uses of wikis: as a tool for online fandom.