Theatre with no script: everything happens for the first time, in front of you, and it’s gone when it ends.
It has two parents who didn’t know each other. In the US, Viola Spolin invented theatre games in the 1930s to teach children social skills, and her Improvisation for the Theater (1963) became the bible of the Chicago scene that grew into The Second City. In the UK, Keith Johnstone wrote Impro (1979) and invented Theatresports, the seed of Whose Line Is It Anyway?. Johnstone only heard of Spolin in 1966. That’s even why there are two words: impro (Johnstone’s school) and improv (the American one).
The famous rule, “Yes, and…”: accept what your partner offers and add something to it. Plot twist: it doesn’t appear in either book. It comes from the house rules of the Compass Players in the 1950s.
And the one I like best: accept the mistake. Johnstone told his students to fail, fail big and fail happily. If the audience sees you enjoying your mistake, they enjoy it with you; if they see you ashamed, they squirm. In impro a mistake only stays a mistake if you treat it like one: accept it, build on it, and it becomes part of the scene.
This is where I’ll collect the impro exercises I try, each tagged impro so they all show up together. First one: Hondom!, a clap-passing warm-up.
Cousins on the shelf: Nadie sabe nada (radio impro), Glosa and garrotins (improvised sung verse in Catalan) and the Inuit poetry duels (improvised poetry to settle disputes).