Augusto Boal presenting a workshop on the Theatre of the Oppressed in New York City. Riverside Church, May 13, 2008.
Forum theatre is a type of theatre created by the innovative and influential practitioner Augusto Boal as part of what he calls Theatre of the Oppressed 
Boal created Forum theatre as a forum for teaching people how to change their world. While practicing earlier in his career, Boal would apply Simultaneous Dramaturgy.
This was an attempt to undo the traditional actor partition and bring audience members into the performance, to have an input into the dramatic action they were watching. In 2006 it has been recorded as the most used way to help new people in the theatre.
# See also - Joker/Jester/Facilitator/Difficultator - Theatre - Legislative Theatre - Wiki as Theatre - Adam Curtis