The nine defensive positions for a baseball team, shown in what is a typical defensive alignment.

Positions

At any given time during play, there will be somewhere between 14-20 people on the field, including defensive players, offensive players, umpires, and coaches¹. Here, we will list the types of positions those defenders play, along with some positions that are unique to the offense.

Defensively, each team fields nine players at a time, and each player is labelled according to the defensive position to which they have been assigned. Additionally, each defensive position has a number assigned to it that is used in scorekeeping². Almost all of the defensive players will also be offensive players, and vice-versa. Players on the offensive, or hitting, team will usually still be referred to by their defensive positions, though there are some positional terms that only apply to hitters or other offensive players. Here, we will go over most of the people you can see on the field, starting with...

The Outfield

Outfielders have the largest territorial range of any of fielders, and the fewest restrictions on where they can be standing when a pitch is thrown. They must be start in the outfield, in fair territory. That's it. Besides that, each individual outfielder can play as deep (close to the outfield fence) or as shallow (close to the infield) as the situation calls for; they can even station themselves in the infield, if necessary.

Left Field (LF) (7): The left fielder patrols the left third of the outfield, as viewed from home plate. This puts them behind the third base/shortstop parts of the infield.

Center Field (CF) (8): The center fielder patrols the middle third of the outfield. This puts them behind the second base area of the infield, though they will often range into right or left field to track down balls hit into those areas (these are sometimes called the “gaps” in the defense). Due to the amount of territory a center fielder is often asked to cover, the position is considered to be one of the most difficult positions to play, or to play well. The center fielder typically has priority over other outfielders when it comes to making plays.

Right Field (RF) (9): The right fielder patrols the right third of the outfield, as viewed from home plate. This puts them behind the second/first base parts of the infield.

The Infield

Infielders' territory is a little more constricted. Like outfielders, infielders must start in fair territory. Further, infielders cannot be stationed anywhere touching the outfield grass. The dirt boundary of the infield is as far away from the plate as they can get. There's no similar boundary on the interior of the infield, however. Finally, the defense can only stash two infielders on each "side" of the infield— any by "side," we mean the space between first and second, and between second and third. If you imagine a line going from home plate, through second base, you need to have two infielders on either side of that line. If one of those fielders scoots over that line, even a little bit, they can get called for a position infraction, and we'll cover what that means later.

First Base (1B) (3): The first baseman covers the infield territory around first base. When there is no runner on, the first baseman usually plays at a spot that allows them to field balls to that side of the infield, while still having enough time to run back to first when another infielder throws to that base. If there is a runner on first, the first baseman typically plays directly at the base, as part of a defensive strategy, aimed at preventing stolen bases, known as "holding the runner on".

Second Base (2B) (4): The second baseman is one of two fielders who makes plays at second base (the shortstop is the other). Even though they must start in the infield, second basemen frequently ranges into the outfield to catch pop-ups or to field ground balls.

Shortstop (SS) (6): The only pure infield position not to be named after a base. The shortstop’s territory ranges between second and third base. Due to the large number of balls his into this area, shortstop is generally thought of as one of the most demanding defensive positions, as shortstops typically have to range far to their right to field balls, or run back to their left to cover second base, or drift back into the outfield, depending on the play.

Third Base (3B) (5): The third baseman covers the area around third base, with their territory overlapping with the shortstop's. The third baseman typically plays closer to home plate than other infielders; this, along with the fact that they will typically face a higher rate of hard-hit balls, gives the position the nickname of “the hot corner.”

The Battery

The term "battery" refers to the pitcher/catcher combination. While both positions are at the very least infield-adjacent, neither is considered to be an infield position. Also, these positions have the least leeway when it comes to positioning.

Catcher (C) (2): The catcher position is orders of magnitude different from the other positions on the field. Catchers sit behind home plate— technically in foul territory— and their main job is to receive the pitches that the pitcher throws, and to receive them in such a way that the umpire thinks that they are strikes. Often, catchers also “call” the pitches that the pitcher is going to throw, as well³, a job that includes working with pitchers, both to understand which of their pitches match a particular situation, as well as attempting to manager their mental/emotional states. Catchers are also in charge of attempting to cut down base stealers, and all the while they are moving up and down behind home plate, getting pelted by foul balls. Which is all to say: catchers, as a breed, are tough. Very tough.

Pitcher (P) (1): The pitcher is the one who pitches the ball towards the batter, and thus sets everything else that happens in motion. They stand at the top of the pitcher’s mound, and there are a whole lot of rules that cover what they can or can’t do up there, but we’ll keep things simple for now. Unlike the other fielding positions, pitchers are not required to also bat, unless something goes wrong. There are a couple main ways to characterize pitchers. One is handedness; pitchers are either a Right Handed Pitcher (RHP) or a Left Handed Pitcher (LHP)⁴. The other is the pitcher’s role, where there are two broad categories: Starting Pitchers, and Relief Pitchers.

• Starting Pitchers: These are the pitchers that start games. In baseball's distant past, a good starting pitcher would be expected to finish a game that they started, though over time, such games have become increasingly rarer (for a variety of different reasons)⁵. Now, if a starting pitcher can average at least 6 innings a start, they’re probably doing something right. Teams will usually have five official starting pitchers on their roster at all times; this is known as a “starting rotation.” Once the starting pitcher is done, they turn the pitching over to the relief pitchers.
• Relief Pitchers: Relief pitchers are the pitchers charged with getting the rest of the outs once the starting pitcher has left the ball game. Each reliever must face at least three batters, or pitch to the end of an inning, before they can be replaced. A team’s full collection of relief pitchers is known as the “bullpen”; this term also refers to the area of the ballpark where relievers wait and warm up before entering the game. Most relief pitchers don’t have a pre-defined “role” within a bullpen, and will instead be summoned into a game based on how the game is unfolding. The exceptions are that late in games, bullpens will often have one or two members defined as “setup men,” who will pitch before the final “closer” comes into a game, typically to preserve the win. As there is less margin for error the later in the game you go, these roles are typically given to relievers who are considered more dependable than the other pitchers. Occasionally, a team may find itself in a position where its manager feels that they would rather not use any of their “real” pitchers. In these cases they can turn to a “position player pitcher,” which is pretty much what it sounds like: a player who usually plays another defensive position, brought in to pitch. While some such players may have prior experience in pitching, most don't, and their style is less about “pitching” and more about “lobbing the ball in, trying not to get hurt.” As these appearances indicate that a game is no longer competitive, MLB has rules about when a position player pitcher can be deployed⁶.

Designated Hitter (DH): Unlike the other positions listed here, the designated hitter is a purely offensive position that never takes the field defensively. Instead, the designated hitter takes the pitcher’s place within the offensive lineup. Why? Because over the course of baseball history, there is one constant: pitchers, as a class, are horrible hitters. The Designated Hitter works⁷ to replace the pitcher with a competent hitter (a hitter who, by the way, might also not be a very good fielder). No other player can be replaced in the lineup in such a way. If the Designated Hitter moves into a defensive position, then their team loses the DH, and their pitcher(s) must go into the lineup. There is an exception made here for so-called “two-way” players⁸: pitchers who can hit well enough to serve as their team’s designated hitter. These players essentially serve two positions at the same time, as a pitcher and a DH. When they leave the game as a pitcher, they can then continue on as a DH, though as a DH they are still subject to the same rules as anyone else; if they move into a non-pitcher position, their team loses the DH.

Base Coaches: The team who is up to bat has two base coaches on the field, positioned in the coaching boxes⁹ behind first- and third-base. They are responsible for relaying signals to the batter or runners between pitches— mostly about if a runner should or should not attempt to steal a base, or if a batter should or should not offer at the next pitch. During play, they are responsible for directing runners around the base paths; the third-base coach is especially critical in this regard as runners coming into third will usually have their backs to whatever is happening in the field, and the the coach’s job is to tell them if they should hold at third, or attempt to score.