The unifying characteristic of comedy TV shows is, of course, humor. Humor has been an important part of television programming since the beginning of the medium. Early variety shows pulled performers and types of performances from popular theater and vaudeville shows. The comedy genre has remained a staple of TV programming. It has evolved into a variety of different forms, including situation comedies, sketch comedy shows and comedic talk shows.
The situation comedy, or sitcom, was the most popular and influential type of TV comedy during the last half of the twentieth century. Variety shows featured a series of stand-alone, unconnected comedy vignettes. Sitcoms feature recurring characters in settings and contexts. In some sitcoms, ongoing story arcs span multiple episodes. A common format emerged for sitcoms-multiple cameras.
The comedy-drama form appeared in the later part of the twentieth century. These shows combine comedic elements with more serious situations that don't aim for laughs. The format of comedy-drama programs typically differs from that of a sitcom. It includes no live audience or laugh track, an hour in length, and more complex editing.
The variety show evolved into a number of other comedic program forms. Sketch comedy shows, in which a series of unrelated vignettes are presented, were especially popular in the 1970s and 1980s. Series such as "Saturday Night Live" draw on current events and popular culture for their satiric sketches. The comedic current-events talk show rose in popularity at the beginning of this century. These shows use comedy as a forum for discussion of political issues and events in the news.