BarCamp is an international network of user-generated conferences (or unconferences). They are open, participatory workshop-events, whose content is provided by participants.

BarCamps are organized and evangelized largely through the web; anyone can initiate a BarCamp using the BarCamp wiki.

The procedural framework consists of sessions proposed and scheduled each day by attendees, mostly on-site, typically using white boards or paper taped to the wall.

Although the format is loosely structured there are rules at BarCamp. All attendees are encouraged to present or facilitate a session. Everyone is also asked to share information and experiences of the event via public web channels including blogs, photo sharing, social bookmarking, twitter, wikis, and IRC. This encouragement to share is a deliberate change from the “off-the-record by default” and “no recordings” rules at many invite-only participant driven conferences. It also turns a physical, face-to-face event into a ‘hybrid event’ which enables remote online engagement with Barcamp participants.

Source: Wikipedia