There's no doubt that baseball and softball are complex games that are tough for a person to learn if they haven't followed it for their entire lives. There are many, many more rules than the ones below, and exceptions to a majority of them. Here's a simple rundown so that a novice can understand the game without getting too bogged down in the details.
A baseball/softball game is played by two teams who alternate between offense and defense. There are nine players on each side. The goal is to score more runs than the opponent, which is achieved by one circuit of four bases that are placed on the diamond.
The defense wears leather baseball or softball gloves that fits on the hand. It's used to catch the ball. A baseball is a white ball roughly three inches in diameter with red stitching. A softball is about twice as big as a baseball and is sometimes yellow. Contrary to the name, a softball isn't softer than a baseball.
The offense uses a bat, which is made of wood in the professional ranks, and made of aluminum or a metal composite at amateur levels. Almost all softball bats are aluminum or metal.
The part of the field closest to the bases is called the infield and the grassy area beyond it is called the outfield.
The bases are 90 feet apart on the diamond, closer in children's leagues and softball. Field areas may differ in a few ways including in the outfield fences or the amount of foul territory, which borders the field between the long white lines that connect first base to home plate and third base to home plate.
There's a pitcher in the middle of the infield who initiates the action by throwing the ball toward home plate. The catcher catches the ball if it's not hit. The infielders are the first baseman, second baseman, shortstop (between second and third base) and the third baseman. There are three outfielders: The left fielder, center fielder, and right fielder.
There are nine innings in professional baseball games (sometimes fewer in lower levels), and each inning is divided in half. In the top of an inning, the visiting team hits and the home team plays defense. In the bottom of the inning, the home team hits and the visiting team plays defense.
Each team gets three outs in each half of an inning.
Each team has nine players in its batting order, and they must stick to that order throughout the game (players may substitute in for other players). A play begins with a batter waiting to hit a pitch from the pitcher. If the batter hits the ball into the field of play, the batter runs to first base and can run to as many bases as he or she deems fit without getting out.
A batter gets three strikes (a swing and a miss or a ball over the plate in what's deemed the strike zone (by an umpire) or he or she is out. If there are four balls (a pitch that is not in the strike zone), the batter is automatically allowed to go to first base.
When a batter begins running, he or she is then referred to as a runner. Runners attempt to reach a base, where they are safe and can remain on the base until the next hitter comes up. The defensive players attempt to prevent this by putting the runners out using the ball; runners put out must leave the field.
A batter gets a hit when he or she reaches a base without getting out or forcing another runner to get out (and without the defense making an error). Runs are scored when a player completes a circuit of the diamond before there are three outs in the inning.
If a player hits the ball over the outfield fence in fair territory (between the foul lines), it's a home run, and the batter can circle all four bases.
There are many ways that the team on defense can get an offensive player out. Four common ways are:
In fast-pitch softball, the pitcher throws the ball underhand instead over overhand, and the field is about 1/3 smaller all around. Games typically last only seven innings.
On the championship/Olympic level, softball is a women's sport, but both sports are played by men and women throughout the world. Slow-pitch softball, when the pitch is underhand and lobbed, is generally played on a recreational basis.