An expression in baseball used to describe the deliberate inaction by a batter toward a pitch delivered to the plate.
When a batter takes a pitch, he is intentionally declining to swing, and usually displays body language that communicates his intentions. The reason behind taking a pitch is the batter believes the pitch will not be thrown as a strike. Depending on the count, it can be more likely or less likely that a batter will take a pitch. The most predictable count in which batters take a pitch is three balls and no strikes. Since one more ball would put the hitter on base, he can afford to take a pitch, even if it ends up as a strike. All this of course depends on a particular batter's strategy, input from managers and coaches, and how well a batter has recently been performing.
More patient batters will often take more pitches out of the strike zone, because they are better at anticipating a pitcher's strategy (and more comfortable in the batter's box), while batters who are in the middle of a hitting slump might swing at even very bad pitches. Batters also tend to take more pitches when the pitcher they are facing has illustrated wildness and lack of control during the game.