Umpire (baseball) in the context of "Strike zone"

In baseball, a baserunner is safe when he reaches a base without being put out by various ways. While a runner is touching a base, he is usually not in jeopardy of being put out, and is thus "safe" from fielders' actions, such as tags. The runner is in jeopardy once again, negating this safety, when:

• he ceases touching the base
• he is forced to reach another base on a force play or when tagging up
• a runner further along the basepath legally returns to the base that he is touching (two runners on the same base)
• he commits interference.

By the rules, a runner is safe when he is entitled to the base he is trying for. Umpires will signal that a runner is safe by extending their elbows to their sides and then extending their arms fully to the side. For emphasis, an umpire may fully cross and extend his arms several times to indicate safe. Verbally, the umpire will usually simply say "safe". If a close play occurs that may have appeared to be a putout, the umpire will also call a reason for the safe call, such as "he dropped the ball" or "he missed the tag".

In baseball, an out occurs when the umpire rules a batter or baserunner out. When a batter or runner is out, they lose their ability to score a run and must return to the dugout until their next turn at bat. When three outs are recorded in a half-inning, the batting team's turn expires.

To signal an out, an umpire generally makes a fist with one hand, and then flexes that arm either upward, particularly on pop flies, or forward, particularly on routine plays at first base. Home plate umpires often use a "punch-out" motion to signal a called strikeout.

In baseball, the strike zone is the area of space through which a pitch must pass in order to be called a strike even if the batter does not swing. The strike zone is defined as the volume of space above home plate and between the batter's knees and the midpoint of his torso. Whether a pitch passes through the zone is decided by an umpire, who is generally positioned behind the catcher.

Strikes are desirable for the pitcher and the fielding team, as three strikes result in a strikeout of that batter. A pitch that misses the strike zone is called a ball if the batter does not swing at it. Balls are desirable for the batter and the batting team, as four balls allow the batter to take a "walk" to first base as a base on balls.

In baseball, fielder's choice (abbreviated FC) refers to a variety of plays involving an offensive player reaching a base due to the defense's attempt to put out another baserunner, or the defensive team's indifference to his advance. Fielder's choice is not called by the umpires on the field of play; rather, it is recorded by the official scorer to account for the offensive player's advance without crediting him with an offensive statistic such as a hit or stolen base.

Though there are several definitions of fielder's choice, the most common (and the only one commonly referred to as FC) involves a fielder fielding a fair ball and choosing to try to put out another baserunner, thereby allowing the batter-runner to safely reach first base. This could be because the defensive player believes they do not have a reasonable prospect of preventing the batter-runner from reaching first base safely, but is usually because it is typically more beneficial for the defensive team to prevent another baserunner from advancing closer to home plate or scoring a run. If another runner is retired on a force out, the batter will not be rewarded with a hit and will be scored a fielder's choice (FC). Other plays that fall under the definition of FC are usually referred to using other terms such as "defensive indifference" or "on the throw."

The commissioner of baseball is the chief executive officer of Major League Baseball (MLB) and the associated Minor League Baseball (MiLB) – a constellation of leagues and clubs known as "organized baseball". Under the direction of the commissioner, the Office of the Commissioner of Baseball hires and maintains the sport's umpiring crews, and negotiates marketing, labor, and television contracts. The commissioner is chosen by a vote of the owners of the teams. The incumbent MLB commissioner is Rob Manfred, who assumed office on January 25, 2015.

Catcher is a position in baseball and softball. When a batter takes their turn to hit, the catcher crouches behind home plate, in front of the (home) umpire, and receives the ball from the pitcher. In addition to this primary duty, the catcher is also called upon to master many other skills in order to field the position well. The role of the catcher is similar to that of the wicket-keeper in cricket.

Positioned behind home plate and facing toward the outfield, the catcher can see the whole field, and is therefore in the best position to direct and lead the other players in a defensive play. The catcher typically calls for pitches using PitchCom, or hand signals. The calls are based on the pitcher's mechanics and strengths, as well as the batter's tendencies and weaknesses. Essentially, the catcher controls what happens during the game when the ball is not "in play". Foul tips, bouncing balls in the dirt, and contact with runners during plays at the plate are all events to be handled by the catcher, necessitating the use of protective equipment. This includes a mask, chest and throat protectors, shin guards, and a heavily padded catcher's mitt. Though rare, some chest protectors may extend lower to provide some shield to the genitalia; wearing a pelvic protector or cup, depending on the case, is preferred and more common.

In baseball, the rules state that a batted ball is considered in flight when it has not yet touched any object other than a fielder or his equipment. Such a ball can be caught by a fielder to put the batter out.

Once a batted ball touches the ground, a fence or wall, a foul pole, a base, the pitcher's rubber, an umpire, or a baserunner, it is no longer in flight. A batted ball that passes entirely out of the playing field ceases to be in flight when that occurs; if it was between the foul poles at that moment, then it is a home run which entitles the batter (and any other runners on base) to score.