Softball, a variant of baseball, was invented as an indoor recreation in Chicago in 1887 by newspaper reporter George Hancock. In the period prior to 1900, the game began to be played outdoors, using a larger ball than employed in baseball, and on a smaller playing field. Variously known throughout the American Midwest and Canada as "kitten ball" and "pumpkin ball," the name softball was formally adopted in 1926. Women had participated in organized softball since the early 1900s.

The United States has been the dominant force in softball since the game's invention. The National Softball Association became the governing body in the United States for the sport, an organization that led to the standardization of the rules of the sport (which had varied significantly from region to region) in 1933. Softball began to slowly develop an international constituency following the end of World War II, which spurred the formation of the world governing body for softball, the International Softball Federation. The first world championships were convened for both men and women in 1966.

While men's softball continued to be played in various countries around the world, softball became more closely associated with female competition. The National Collegiate Athletic Association (NCAA) sponsored its first-ever American intercollegiate women's national softball championship in 1982; over 600 institutions now participate in one of three competitive divisions. Softball has the distinction, along with the sport of field hockey, of being one of only two sports exclusively reserved for female competition in the NCAA.

The culmination of the progress of women's softball as a world sport occurred with the designation of softball for inclusion as a full medal sport at the 1996 Olympic Summer Games in Atlanta; softball was also contested in the 2000 and 2004 Summer Olympics. However, in 2006, the International Olympic Committee (IOC) voted to discontinue both softball and men's baseball as Olympic competitions after the 2008 Olympics in Beijing. The IOC decision was a curious one, given the stated goal of the IOC to ensure that in time, the Olympics would have an equal number of men's and women's competitions.

Softball, as regulated by the National Softball Association, developed two distinct variants: fast-pitch softball and slow-pitch softball, a game sometimes described as simply slow-pitch or lob-ball. The chief distinction between the two games is with respect to the speed with which the pitcher is permitted to deliver the ball to the batter, and the corresponding response of the defensive team to the batted ball. Slow-pitch is an extremely popular game in North America, played by men, women, and in coed formats, in both recreational and competitive leagues.

The rules of fast-pitch softball create a game that is similar to baseball in terms of the number of players, the shape of the field, equipment, and the general strategies to be employed both offensively and defensively. The game is played with nine players in the field, including four infielders, three outfielders, a pitcher, and a catcher. Each team is permitted to bat until they make three outs. When each team has been to bat for three outs each, an inning is concluded. There are seven innings in a softball game.

Softball is played on a field popularly known as a diamond, given its shape; the field may not be any longer than 225 ft (68 m) from home plate to the outfield fences. The field is divided into an infield, which is defined by the positioning of four bases, and the outfield, the area between the infield and the outfield fences. The infield is comprised of four bases, commencing at home plate. The bases are 60 ft apart (18 m).

The pitcher delivers the ball toward home plate from a pitcher's plate (often referred to as "the pitching rubber"), which is 43 ft (13 m) from home plate. The pitch must be delivered in an underhanded motion, known as a "windmill" motion. The pitcher's rear foot must remain in contact with the pitcher's plate throughout the delivery. Women's softball does not permit a hop or jump in the pitching motion, while men's softball permits a hop movement, which permits the pitcher to deliver the ball with greater velocity.

All players wear cleated shoes and uniforms; all defensive players use a fielding glove designed for the particular position played. The catcher wears equipment for safety, including shin guards, a chest protector, helmet and face mask, and heavily padded glove. Players may be substituted, but once a player is replaced in the course of the game they are not permitted to return to play.

The ball, at 12 in (30 cm) circumference, must have a coefficient of restitution (COR) of a maximum 0.47. This characteristic comes into clearer focus when contrasted with the legal COR for a baseball, which by rule must be between 0.514 and 0.578. The lower the COR of any material, the less energy is returned to any object coming into contact with it. The lower COR of a softball is an important distinguishing factor in the distances traveled by it when compared to a baseball when struck with a bat.

The bat has regulated dimensions of length, weight, and circumference; the most important aspect of a softball bat is its construction, which typically is aluminum or a composite metal material.

Unlike baseball, where a base runner is permitted to lead off from the base in preparation for either attempting to steal the next base or to secure a advantage if the ball is put into play, the softball base runner may not leave the base until the ball is struck by the batter.

The general offensive and defensive strategies employed in softball are similar to those used in baseball. Offensively, the team attempts to advance its players around the bases to score runs by hitting, running the bases, and advancing their base runners through devices such as when a batter "sacrifices" an out to permit a teammate to gain an extra base. Another strategy is drawing a walk, the one-on-one battle with a pitcher where the pitcher throws four balls before he or she is able to either throw three strikes over the plate or otherwise induce the batter to hit the ball until he or she is out. It is the differing role of the pitcher in each sport that defines the strategic differences.

In both baseball and softball, a talented pitcher is the key to team success. In softball, that importance is magnified by a number of factors. The pitching

Female softball player waiting for a throw.
mechanism permitted in softball places a lesser amount of stress on the pitcher's shoulder and elbow than does the overhand mechanism of the baseball pitcher, who is the most player most injured in baseball. Softball pitching and its fluid, natural rotation of the shoulder, coupled with a forward stride, permit the softball pitcher to pitch with less risk of either injury or fatigue, while maintaining pitch velocity.

In baseball, it is common for modern pitchers to be relieved after six or seven innings of the standard nine inning game, with the pitcher resting for three days following the game. In softball, a dominant pitcher can often pitch with less rest. In the 1970s, the softball world's most dominant pitcher, Canada's Pete Landers, regularly pitched complete games in both ends of a doubleheader (two games played consecutively in a single day).

Pitching dominance and a less lively ball place a premium on what is sometimes referred to as "small ball." Batters seek to get the ball in play, where the fielder must make a throw and the batter hopes to cover the 60-ft (18 m) distance to first base in advance of the throw. With the same number of players on a surface that is at least 35% smaller than in baseball, coupled with the greater ability of the pitcher to dominate the hitter due to the reduced distance between the two opponents, the ability to hit the ball to a vacant area on the field is correspondingly reduced.

The game of slow-pitch is also governed in the United States by the National Softball Association, but the game has taken a developmental path that is strikingly different than that of its fast-pitch cousin. Slow-pitch has a tremendous recreational appeal due to the fundamental distinction as to the role of the pitcher: in slow-pitch, the unstated premise of the game is that the ball will be put into play by every batter. Given the greater emphasis on offense in slow-pitch, the game provides for 10 players, with an additional outfielder. The other equipment used by the players is similar to that of fast-pitch. At the elite levels of slow-pitch, the bases may be set 65 ft or 70 ft (20-21 m) apart.

SEE ALSO Baseball; Exercise, intermittent; Motor control; Softball: Slow pitch vs. the fast pitch.