A type of out that is made in the field of play including fly outs, tag outs, force outs and any outs due to illegal plays. The other type of out is a strikeout, which is made by the pitcher. For each play where the out occurs in the field of play, the player that is most directly responsible for the out will receive a recorded putout.
Credit for the putout is determined based on a set of considerations depending on the type of out. For a fly out, the player must catch the ball without it touching the groud and then must be voluntarily released by that player. In the case of tag out, it's the defensive player who tags the runner who will receive credit for the putout. For force outs it's the fielder on the bag who receives credit.