A single game is played by two teams, who, during the course of a game, alternate playing offense and defense. A "season" is played over the course of many months by a group of teams, called a league. Each team in the league plays all the other teams in the league a fixed number of times, though it is not always in round robin format. At the end of the season, the team with the most wins is the winner of the regular season.
The goal of a game is to score more points, which are called "runs" in the language of baseball, than the other team. Each team, usually composed of 9 or 10 players, attempts to score runs while on offense, by completing a tour around (in counter-clockwise order, beginning at the home plate) the bases, which form a square-shaped figure called a "diamond," see the image below.
There are four basic tools of baseball: the bat, the ball, the mitt, and the field.
- The bat is an offensive tool, either made of wood or aluminum depending on the game being played. It is a long, hard stick, about 2 inches (5 centimeters) in diameter, except at the handle, which is about 1-inch (2.5 centimeters) diameter.
- The ball is white for baseball (though other colors can be used) with red lacing about the size of a fist. Softball uses a white or yellow ball (usually) with white lacing about the size of two fists.
- The glove or mitt is a defensive tool, made of leather, worn on the players hand to aide in catching the ball. It takes various shapes to meet the uniques needs of the defensive position of the player.
- The game is played on a field, whose dimensions vary depending on the age of the players. However, every field has a diamond, with bases at its corners, that the offensive players circumnavigate, as mentioned above. That part of the field close to the bases is called the infield, and that part distant from the bases is called the outfield.
To begin a game, the "home" team plays defense first, so the nine defensive players go out onto the field, attempting to prevent the opposing team from scoring. The "visiting" team plays offense first, and therefore attempts to score runs. Runs are scored as follows: starting at home plate, each offensive player attempts to earn the right to run (counterclockwise) to the next base (corner) of the diamond, then to touch the base at that corner, continuing on to each following base in order, and finally returning to home, whereupon a run (point) is scored.
Before the running of bases can begin, a defensive player called the "pitcher," stands at the center of the diamond on a designated spot, called the mound or the rubber - a reference to a rectangular plate at the center of the mound. The other eight or nine players are on the field, simultaneously with the pitcher, standing in various positions.
An offensive player called a "batter" stands at home plate, holding a bat. The batter then waits for the pitcher to throw the ball toward home plate. At the appropriate time, the pitcher throws the ball, called a pitch, toward the batter, who attempts to hit the ball with the bat. If the batter hits the ball into play, the batter must then drop the bat and begin running toward 1st base. (There are other ways to earn the right to run the bases, such as walks or being hit by a pitch. See baseball for more.)
When a batter begins running, he or she is then referred to as a runner. At this point, the runner attempts to make it to a base and is either called "safe" allowing him or her to stay on a base, or the runner fails to reach the base, called an "out." When an "out" occurs, the runner must leave the field (returning to the "bench" or "dugout", the location where all the other inactive players and managers observe the game).
There are many ways that the team on defense can get an offensive player out. For the sake of simplicity, only the five most common ways are listed here:
- the "strike-out": while still at home plate, the batter fails to earn the right to run the bases. A strike-out occurs when the pitcher successfully thwarts the batter's attempts to hit the ball.
- the "ground out": should the batter hit the ball on the ground, a defensive player can retrieve the ball, and throw it to another defensive player standing on first base before the runner arrives at first.
- the "force out": occurs when a runner is required to run to a base (by rule) but fails to reach a base before the ball reaches the defensive player standing on the base. The "ground out" is one of many types of outs called "force outs."
- the "fly out": should the batter hit the ball in the air, the defense can catch the ball before it hits the ground, earning an out.
- the "tag out": while between bases, a runner is out if a defensive player touches the offensive player with a held ball.
A game of baseball is divided into multiple "innings," where each team takes a turn playing defense and then offense, or vice versa. An inning is comprised of 6 "outs", 3 for each team. When the defensive team gets three of the offensive players "out," the teams switch roles, offense to defense and vice-versa. Depending on the type of "ball" being played, each team receives up to 9 attempts to score runs.
The rules of baseball are much more complicated than can be presented here. A summary of these rules is on the baseball page.