Hide-and-seek (sometimes known as hide-and-go-seek) is a popular children's game in which at least two players (usually at least three) conceal themselves in a set environment, to be found by one or more seekers. The game is played by one chosen player (designated as being "it") counting to a predetermined number with eyes closed while the other players hide. After reaching this number, the player who is "it" calls "Ready or not, here I come!" or "Coming, ready or not!" and then attempts to locate all concealed players.

Source: Wikipedia