Sketch comedy comprises a series of short comedy scenes or vignettes, called "sketches", commonly between one and ten minutes long. Such sketches are performed by a group of comic actors or comedians, either on stage or through an audio or visual medium such as radio and television. Often sketches are first improvised by the actors and written down based on the outcome of these improv sessions; however, such improvisation is not necessarily involved in sketch comedy.
An individual comedy sketch is a brief scene or vignette of the type formerly used in vaudeville, and now used widely in comedy and variety shows, talk shows and some children's television series (such as Sesame Street).
Sketch comedians routinely differentiate their product from a "skit", maintaining that a skit is a (single) dramatized joke (or "bit") while a sketch is a comedic exploration of a concept, character or situation.
Sketch comedy has its origins in vaudeville and music hall, where a large number of brief, but humorous, acts were strung together to form a larger programme.
In Britain, it moved to stage performances by Cambridge Footlights, such as Beyond the Fringe and A Clump of Plinths (which evolved into Cambridge Circus), to radio, with such shows as It's That Man Again and I'm Sorry, I'll Read That Again, then to television, with such shows as Not only... But Also, Monty Python's Flying Circus, Not the Nine O'Clock News (and its successor Alas Smith and Jones), and A Bit of Fry and Laurie.