As far as content is concerned, comedians such as Tommy Tiernan, Des Bishop, Kevin Hart, and Dawn French draw on their background to poke fun at themselves, while others such as Jon Stewart, Ben Elton and Sarah Silverman have very strong political and cultural undertones.

[citation needed] Comedians can be dated back to 425 BC, when Aristophanes, a comic author, and playwright, wrote ancient comedic plays.

A Shakespearean comedy is one that has a happy ending, usually involving marriages between the unmarried characters, and a tone and style that is more light-hearted than Shakespeare's other plays.

[8] Bob Hope became the most popular stand-up comedian of the 20th century in a nearly 80-year career that included numerous comedy film roles over a five-decade span in radio, television, and entertaining armed-service troops through the USO.

Other noted stand-up comedians include Lenny Bruce, Billy Connolly, George Carlin, Richard Pryor, Victoria Wood, Joan Rivers, Whoopi Goldberg and Jo Brand.

In 1968, radio surreal comedy group The Firesign Theatre revolutionized the concept of the spoken comedy album by writing and recording elaborate radio plays employing sound effects and multitrack recording, which comedian Robin Williams called "the audio equivalent of a Hieronymous Bosch painting."

Radio comedy began in the United States when Raymond Knight launched The Cuckoo Hour on NBC in 1930,[12] along with the 1931 network debut of Stoopnagle and Budd on CBS.

Most of the Hollywood comedians who did not become dramatic actors (e.g. Bergen, Fields, Groucho and Chico Marx, Red Skelton, Jack Benny, Fred Allen, Judy Canova, Hope, Martin and Lewis), transitioned to United States radio in the 1930s and 1940s.

On television there are comedy talk shows where comedians make fun of current news or popular topics.

Such comedians include Jay Leno, Conan O'Brien, Graham Norton, Jim Jefferies, James Corden, John Oliver, Jonathan Ross, David Letterman, and Chelsea Handler.

Other joke forms include observation (Michael McIntyre), whimsy (David O'Doherty), self-deprecation (Robin Williams) and parody (Diane Morgan).

In a January 2014 study, conducted in the British Journal of Psychiatry, scientists found that comedians tend to have high levels of psychotic personality traits.

They found that comedians scored "significantly higher on four types of psychotic characteristics compared to a control group of people who had non-creative jobs."

Gordon Claridge, a professor of experimental psychology at the University of Oxford and leader of the study claimed, "the creative elements needed to produce humor are strikingly similar to those characterizing the cognitive style of people with psychosis—both schizophrenia and bipolar disorder.

"[17] However, labeling comedians' personality traits as "psychotic" does not mean that individual is a psychopath,[18][19] since psychopathy is distinct from psychosis, and neither does it mean their behavior is necessarily pathological.

[21] In that year, the eight highest paid comedians were from the United States, including Amy Schumer, who became the first woman to be listed in the top ten.