In baseball, the umpires are the officiators of the game. They ensure that all players and coaches are following the rules, and they make many crucial decisions that determine the outcome of pitches and plays.
There are usually three umpires in a baseball game:
To communicate their decisions, umpires make calls. These calls involve yelling out certain words or phrases, accompanied with specific hand signals.
Umpires officiate the game; they are unbiased observers who make official decisions that determine the outcome of the game. They perform many duties before the game as well, such as checking players' equipment, the lines on the field, and the condition and number of baseballs available for play. While the manager is responsible for producing two copies of their lineup card, the umpire ensures that both copies are identical. For reference, each team gets a copy of the other team's lineup card.
At the start of each game, the umpire checks equipment of players, checks the ground lines for chalk, checks regulation baseballs from home club for certification and that gloss is removed, checks that a dozen reserve balls are available, official rosin bag is placed on ground behind the pitcher's plate before the start, he has two alternate balls in his possession to replace if pitcher requests new one, ball becomes unfit for play, or it flies into spectator area.
The Umpire In Chief
The plate umpire is the final decision maker. He is responsible for all major decisions and calling pitches strikes or balls while standing in the batter's box behind the batter and catcher. Only the team captains can make an appeal to the plate umpire without the risk of being ejected from the game.
To start the game, the umpire yells, Play! and points at the pitcher with his right hand. He also calls Play to start the game again after a dead ball, once the pitcher, catcher, and batter are ready.
To signal that the pitch was a strike, the home plate umpire makes a fist with his right hand and makes a single, quick pounding motion. Some umpires also use their right hand to point to the side, also signaling a strike. If the strike was a called strike, meaning the batter did not swing and the ball went through the strike zone, the umpire will yell, Strike. However, if it was a swinging strike, meaning the batter swung at the pitch and missed, the umpire usually will not verbalize.
The umpire also determines strikes based on how the batter reacts to the pitch and where it ultimately ends up. Strikes are always called when a batter swings and misses. So, if a batter swings at a pitch he essentially the umpire disregards the strike zone. A ball can never be called when a batter takes a swing. So even if the ball was thrown outside the strike zone it's a strike if he misses. All the credit to the batter if he can successfully hit the ball on a pitch outside the strike zone, a decision he must make.
To signal that a player is out, the umpire makes a fist with his right hand, then makes a single, quick hammer motion. The personal style of the out call, especially in the Major Leagues, varies depending on the umpire, but it is usually pretty clear what the call is. They also often call, Out! as they make the arm motion.
To signal that a runner is out, the umpire that is closest to the players will make the safe call. To do this, the umpire spreads his arms out horizontally, with his palms facing the ground. If it was a close call, meaning it was hard for observers to tell for certain if the runner was out, the umpire will also yell, Safe!