A warm-up comedian or crowd warmer is a stand-up comedian who performs at a comedy club or before the filming of a television comedy in front of a studio audience to get the crowd into the mood ready for the show or main act. Their role is to make the audience feel integral to the show and encourage reactions during the show.
They usually work alone and perform a comedy routine while also possibly explaining aspects of the show. They will also perform during commercial breaks. Some warm-up routines before talk shows involve giving prizes to audience members. The use of warm-ups dates back before television to radio shows.