The name BarCamp is a playful allusion to the event's origins, with reference to the programmer slang term, foobar: BarCamp arose as an open-to-the-public alternative to Foo Camp, which is an annual invitation-only (for Friends of O'Reilly) participant-driven conference hosted by Tim O'Reilly.
The first BarCamp was held in Palo Alto, California, from August 19–21, 2005, in the offices of Socialtext. It was organized in less than one week, from concept to event, with 200 attendees. Since then, BarCamps have been held in over 350 cities around the world, in North America, South America, Africa, Europe, the Middle East, Australasia and Asia. To mark the first anniversary of BarCamp, BarCampEarth was held in multiple locations world wide on August 25–27, 2006.
The second anniversary of BarCamp, BarCampBlock, was held in Palo Alto at the original location, but also over a three block radius on August 18–19, 2007, and was attended by over 800 people.
The largest recorded BarCamp happened in February 2011 with over 4700 confirmed registered attendees in Yangon, Myanmar (Burma). The previous year (January 2010) BarCamp Yangon attracted over 2700 attendees (confirmed with registration forms) Barcamp Yangon in Global Voices.