In Man, Play and Games, Caillois investigates the phenomenon of play, which he describes as "an occasion of pure waste: waste of time, energy, ingenuity, skill, and often of money." Caillois defines play as a free and voluntary activity that occurs in a pure space, isolated and protected from the rest of life. Play is uncertain, since the outcome may not be foreseen, and it is governed by rules that provide a level playing field for all participants. In its most basic form, play consists of finding a response to the opponent's action--or to the play situation--that is free within the limits set by the rules.
Caillois develops a matrix of types of game, based on whether the role of competition, chance, simulation, or vertigo (being physically out of control) is dominant. Against this, he sets a continuum of ways of playing, ranging from the unrestricted, joyful improvisation characteristic of children's play to the disciplined pursuit of solutions to gratuitously difficult puzzles. Caillois also examines the means by which games become part of daily life and ultimately contribute to various cultures their most characteristic customs and institutions.