A catcher is said to call the game by sending signs to the pitcher calling for a particular pitch. After he moves into his crouch, the catcher gives the sign by placing his non-glove hand between his legs and using his fist, fingers, wags, or taps against his inner thigh to tell the pitcher what type of pitch to throw (fastball, curve, etc.) as well as the location. A pitcher may shake off (shake his head "no" to) the initial sign or nod in agreement when he receives the sign that he wants before going into his windup. If there is a runner on second base, a catcher may change the location of his glove (from his knee to the ground, for example) to signal the pitcher that he is using an alternate set of signs so that the runner won't be able to steal the sign.

A coach sends signs to players on the field, typically using a sequence of hand movements. He may send signs to offensive players, including batters and runners, about what to do on the next pitch — for example, to sacrifice bunt, to take or to swing away at the next pitch; to steal a base; or to execute a hit-and-run. He may send signs to the catcher to call for a pitchout or to intentionally walk the batter.