Covering a base

In baseball and softball, part of the infielders' and pitcher's jobs is to cover bases.

On a ground ball to either the shortstop or the second baseman, the other of those will cover second base.

[citation needed] If the defense is employing an extreme shift, with the shortstop playing on the first-base side of second base and with the third baseman playing near second base (because by reputation the batter is anticipated to hit the ball to the right side of the infield), in some cases the pitcher may need to cover third base.

[citation needed] When the pitcher throws a wild pitch, or when the catcher permits a passed ball, so that in either case the catcher has to retreat farther into foul territory away from home plate to retrieve the ball, if there is a runner on third base the pitcher will cover home plate.

In American English, the expression "cover your bases" used outside of a baseball setting means to be thoroughly prepared for something.