According to the dictionary, to improvise is "to compose and perform or deliver without previous preparation", to do so "on the spur of the moment" and with "whatever materials are readily available". There are plenty of troupes putting the art of improvisation into practice at this year's Edinburgh Fringe. With this lot, you never know what to expect - except something different at every performance.

1) Aaaand Now for Something Completely Improvised

After a successful 2010 Fringe run, Racing Minds return to Edinburgh with their improv show. At every performance, a new and different play will be improvised, based on audience suggestions. Anything goes at this comedy extravaganza. Laughing Horse@ Meadow Bar, 4-28 August, 12.15.

2) The Oxford Imps

In the style of Who's Line Is It Anyway?, this comedy troupe brings fast-paced stand-up all the way from Oxford. From sketches and musicals to mime and rap, this interactive show depends entirely on audience suggestions. Gilded Balloon Teviot, 2-29 August, 15.45.

3) Showstopper! The Improvised Musical

Via the West End and heading back after the festival, this is the fourth Fringe season for Edinburgh veterans Showstopper Productions. This year they bring new musical theatre created every night from audience suggestions. Gilded Balloon Teviot, 5-28 August, 15.20, times vary.

4) Absolute Improv

This Edinburgh-based improv troupe brings more fast-paced improvisation comedy. With the show based on audience suggestions, all ages are welcome, as long as they are ready to shout out their ideas. TheSpaces on the Mile, 5-27 August, 18.05.

5) Lights! Camera! Improvise!

With improvised musicals and comedy already on the menu, Scat Pack bring an improvised movie live to the stage. The audience choose theme, location and title, and the comedy troupe improvise the film. C Venues - C, 3-29 August, 19.15.

6) The School of Night

Founded by the late experimental theatre maverick Ken Campbell, this group takes on the challenge of creating an authentically Shakespearean masterpiece during their show. Gilded Balloon Teviot, 4-18 August, 17.15.

7) Couch Impro

Make yourself comforable on the therapist's couch as this improv troupe takes on your suggestions on all the ups and downs of life, trying to find a solution to your problems. Might laughter be the best therapy after all? Buffs Club (RAOB), 18-27 August, 22.00.

8) Chimprovisations!

With improv games, guest stand-up comedians, and original sketches and songs, the touring company Monkeys With Puns bring their talent to the Fringe. Spotlites @ The Merchants' Hall, 4-29 August, times vary.

9) The Panther's Scream and Other Texas Tales

This children's show sees a compilation of Texas folklore and legends brought to stage. The show was developed through improvisation by director Patrick Bynane and his cast, and features live music and shadow puppets. TheSpaces on North Bridge, 5-13 August, 10.30.

10) To Hold an Apple

Not by definition an improv show, this play is about three improvisers arguing about the nature of theatre. On the verge of break-up, they decide to improvise together once more. The friendly banter soon turns into a fierce encounter. TheSpace @ Jury's Inn, 5-27 August, 15.10.