What "infielder" means in baseball

In baseball, an infielder is a player who primarily plays defense in the infield, which is the area of the field containing the four bases. Infielders generally include the first baseman, second baseman, shortstop, and third baseman. Their main responsibilities include fielding ground balls, catching pop-ups, and throwing out base runners. Infielders are crucial to the defense and strategy of the team.