The type and sequence of pitches chosen depend upon the particular situation in a game. Because pitchers and catchers must coordinate each pitch, a system of hand signals is used by the catcher to communicate choices to the pitcher, who either vetoes or accepts by shaking his head or nodding. The relationship between pitcher and catcher is so important that some teams select the starting catcher for a particular game based on the starting pitcher. Together, the pitcher and catcher are known as the battery.
