[2] The show consists of a panel of four performers who create characters, scenes, and songs on the spot, in the style of short-form improvisation games.

[3] The original host Drew Carey awarded arbitrary point values after each game, often citing a humorous reason for his decision.

He would reiterate this at the beginning of, and multiple times throughout, each episode by describing Whose Line as "the show where everything's made up and the points don't matter".

In the second season, the reading of the credits was performed by one or more cast members in a comedic fashion, based on a theme announced by Carey that often derived from a successful joke earlier in the show.

The US version also introduced several newcomers, including Denny Siegel, Kathy Greenwood, Jeff Davis, Patrick Bristow (who appeared in one episode of the last UK season), Stephen Colbert, Kathy Kinney, Ian Gomez, Gary Anthony Williams, Jonathan Mangum, Heather Anne Campbell, Keegan-Michael Key and Nyima Funk.

On some occasions, in a feature that was unique to the US version, a celebrity made a guest appearance for individual games; such appearances have included Sid Caesar,[5][6] David Hasselhoff, Florence Henderson, Jerry Springer, Joanie "Chyna" Laurer, Richard Simmons, Katie Harman, Jayne Trcka,[7] the Loyola Marymount University cheerleaders, Hugh Hefner, and Lassie.

From the second season onward, other musicians joined Hall – Linda Taylor made frequent appearances playing guitar and occasionally keyboards, while Cece Worrall-Rubin, Anne King, Candy Girard, and Anna Wanselius appeared alongside Hall (and sometimes also Taylor) on occasion.

Others were new and uniquely created for both the American original format, and the revived show, with several only being played once or twice, due either to the games not having been well received by audiences, or to Stiles' reluctance to perform certain rounds.

There are eight games that have been performed at least once in every season; these are Scenes from a Hat, Greatest Hits, Props, Let's Make a Date, Weird Newscasters, Duet, Helping Hands, and Questions Only.

[8] While Wayne Brady turned out to be well suited to them, having Chip Esten, Jeff Davis, Brad Sherwood and Gary Anthony Williams making frequent appearances as his duet partner, Stiles frequently expressed open disdain towards the "Hoedown" game, which became a bit of a running gag, while Mochrie, who cannot sing, mainly preferred to deliver his lines in a spoken word fashion, much like in the British original.

Ryan Stiles and Colin Mochrie, who would later star in the American version, made their first appearances on the show in seasons 2 (1989) and 3 (1991) respectively.

Other regular performers on the US version who first appeared on the UK original were Greg Proops, Chip Esten, Brad Sherwood, and Wayne Brady.

While Anderson's point-scoring had always been arbitrary as a joke, he still presented the points as though they had real weight towards the final outcome of the episode.

On the US version, the winner would take over as host while Carey took part in the last game of the episode, with the performer(s) who read out the closing credits being arbitrary.

The difference in standards in the UK compared to US prime time meant stricter censoring of both language and content on the US series.

The major gimmick on that series was that the acting was done in front of a green screen, and animators later added cartoon imagery to the scenes.

[10] Colin Mochrie, Brad Sherwood and Drew Carey performed at the Just for Laughs festival in Montreal as "Improv All-Stars" in 2003 and 2004.

In February 2013, Ryan Stiles revealed in an interview that he would be returning to Los Angeles in April for a new season of Whose Line, hosted by Aisha Tyler and featuring the original cast of the U.S.

[15] In addition to the traditional rotating fourth improv player (often drawn from same pool of regulars that appeared on the original show), a new feature was that of a "special guest".

[16][17] On July 29, 2013, The CW announced that it had renewed the show for a 24-episode season, airing Fridays at 8 ET/PT starting March 21, 2014,[18][19] due to solid ratings.

[21][22] After the CW stated that this was inaccurate as no decision had been made yet, Mochrie clarified his comments in a February 2023 interview, saying that the cast never received fair compensation nor were paid residuals.

[23][24] In June 2023, The CW's Head of Unscripted Programming, Heather Olander, stated that she did not know what the future of the series beyond that was and that they had discussed with the cast about whether they wanted to continue with the show.

[26] Several of the performers, including the three regulars Brady, Mochrie, and Stiles, had previously appeared in the original British run of Whose Line; other performers who had made appearances in the British version are Greg Proops, Brad Sherwood, Chip Esten, Karen Maruyama, Patrick Bristow and Josie Lawrence, as well as musician Laura Hall.

Mochrie is the only performer to have appeared in every episode of the American series of Whose Line?, with Stiles having missed two recordings due to illness.

Occasionally more musically inclined guests, like Christopher Jackson, and David Hasselhoff, also partook in singing games.

Improvisational musician Laura Hall, who appeared in the final season of the British original, joined the original American format for its entire run, and performed piano, keyboards and other instruments in games featuring improvisational singing by the cast members, such as Hoedown, Greatest Hits and Songstyles.

It is also available on its on-demand service UKTV Play starting from season eleven onwards, marketed as series three of the revival.

The show's original run in Australia was on the Nine Network in an early morning time slot; One repeated the program from 2011.