Long-form improv is a live performance by an ensemble who make up scenes together on stage without a script. The show begins when one member of the group asks the audience for a suggestion.  Once the suggestion is given the ensemble performs scenes inspired by that suggestion with the focus of the performance being towards creating believable locations, characters, and relationships grounded in truth with their fellow performer on stage.  The entire show is made up on the spot with no decisions made about the content beforehand. The performance typically lasts about half an hour, with a blackout or announcement signaling the end of the show by one of the performers.  Amy Pohler, Mike Myers, Zack Woods, and pretty much every comedic actor you can think of has performed or engaged in long form improv.