This document discusses the history and structure of an "unconference", which is a participant-led conference where discussions and sessions are proposed and planned spontaneously by attendees rather than having an agenda predetermined by organizers. It notes that the first unconferences were TeachMeets in 2006-2010 that lasted 1-2 hours and were volunteer-fueled before being incorporated as edcamp.org. Following the principles of Open Space Technology, unconferences are open format with short, random participant presentations and participant-led discussions determined during zero-hour session planning at the start.