Foul ball

The 1845 Knickerbocker Rules, which laid the foundation for modern baseball, also included the concept of foul territory due to a need to adapt the game when there not enough players;[3] according to Thorn, even home runs were potentially considered foul in this set of rules, since losing the club's only ball in the nearby Hudson River would prematurely end the game.

[5] Until the 1920s, Major League Baseball spectators were often ejected if they attempted to keep foul balls, and teams employed security guards to ensure it.

Factors such as negative public sentiment, a decrease in the cost of baseballs relative to team revenues and increased pressure to discontinue use of worn, damaged and/or discolored baseballs (especially after the death of Ray Chapman) combined to persuade several teams to change their foul ball policies during this period; the New York Giants changed theirs after losing a New York Supreme Court case (Reuben Berman vs. National Exhibition Co.) filed by Reuben Berman.

[6][7] Depending on the exact situation, a foul ball may be considered beneficial to the offense or the defense.

Also, foul balls with two strikes increase the pitcher's pitch count, adding to his/her fatigue, thus providing some small advantage to the offense.

A strategy of swinging on any ball to try to produce additional fouls and prolong an at-bat is often used against strong pitchers to try to drive them from the game sooner (and also the possibility of the pitcher throwing a pitch a hitter can get a hit on); this does, however, have the disadvantage of generating more strikeouts.

[citation needed] In very specific circumstance—such as in the bottom of the ninth inning (or later) of a tie game when a runner is on third base with less than two outs—outfielders may intentionally not catch deep fly balls in foul territory, as catching such a ball would create a sacrifice fly, potentially allowing the winning run to score.