A 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 and/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.
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 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.
There is also the Los Supergenios de la Mesa Cuadrada created by Mexican comedian Chespirito transmitted in Mexico between 1968 and 1973 that created famous characters like El Chavo del Ocho and El Chapulín Colorado and other character like Los Caquitos, Dr. Chapatín and Los Chifladitos.
Historically, the sketches tended to be unrelated, but more recent groups have introduced overarching themes that connect the sketches within a particular show, with recurring characters that return for more than one appearance. Examples of recurring characters include Mr. Gumby from Monty Python's Flying Circus; Ted and Ralph from The Fast Show; The Family from The Carol Burnett Show; the Head Crusher from The Kids in the Hall; Martin Short's Ed Grimley, a recurring character from both SCTV and Saturday Night Live; and Kevin and Perry from Harry Enfield and Chums. The idea of running characters was taken a stage further with shows like The Red Green Show and The League of Gentlemen, where sketches centered on the various inhabitants of the fictional towns of Possum Lake and Royston Vasey, respectively.
In North America, contemporary sketch comedy is largely an outgrowth of the improvisational comedy scene that flourished during the 1970s, largely growing out of The Second City in Chicago and Toronto.
Sketch films are rare, since the genre is associated with TV and theatre. The more popular ones were made during the '70s and '80s: The Groove Tube, Kentucky Fried Movie (and its sequel Amazon Women on the Moon) and the Monty Python movies. There have been a few sketch films in recent times, but they've been critical and financial failures: The Underground Comedy Movie (and its sequel InAPPropriate Comedy) and Movie 43.
Since 1999, the growing sketch comedy scene has precipitated the development of sketch comedy festivals in cities all around North America, including festivals in Boston, Chicago, Los Angeles, New York, Montreal, Portland, San Francisco, Seattle, Toronto, Vancouver, and Philadelphia.