The pitcher is at the center of the action for most of the game, since he delivers the pitches that batters attempt to hit. What the pitcher throws and how the batter responds is the basic structure of the baseball game; it all starts with the pitcher. There are two main types of pitchers in baseball:
Starting pitchers, also known as starters, are the game's main pitchers who pitch starting from the first inning. They often pitch the majority of the game, typically about five to seven innings per game. Of all the pitcher types, starters have the most stamina (since they pitch for several innings) and are usually the most well-rounded, since they must face a myriad of batters and situations.
The ace is the team's best starting pitcher, and often the team's best and most well-known pitcher in general. You can tell who a team's ace is by seeing who the first guy in the rotation is, as that is the spot that the ace almost always occupies. Some of the most exciting games in baseball are when both teams' aces are the starting pitchers for that game.
We will learn more rotations in baseball in the next chapter. For now, you should know that a rotation is fairly similar to a lineup, but with some important adjustments. Just like a lineup, a rotation dictates the order of starting pitchers.
If a starting pitcher pitches the entire game without being substituted, he has achieved what is called a complete game. However, in modern baseball, complete games are becoming more and more uncommon. The next section will discuss games that are not complete games, where the starting pitcher is substituted with another pitcher.
Often, the manager will know or sense beforehand that the starting pitcher needs to be replaced, so he calls a reliever or two to warm up in the bullpen. The bullpen is slightly off the field and contains a pitcher's mound and a home plate so relievers can warm up and simulate real pitching situations, often while a pitching coach acts as the catcher. When the reliever is needed, he exits the bullpen and enters the game. We'll learn more about relievers next.