Two teams of nine players aim to score the most runs by striking a ball and running round a sequence of bases to reach the home plate. The team with the most runs after nine innings of batting and fielding wins.
The teams rotate between batting and fielding, with each session called an inning, and switch when the fielding team gets three opposition players out.
The pitcher throws the ball from a mound toward the catcher which the batter attempts to hit and get around the bases to the home plate.
The rules for softball are mainly the same as in baseball, but there are key differences.
There is a smaller playing area and a shorter distance between the pitcher and batter. The bat is no longer than 34 inches (86cm) compared to 42 inches (106cm) in baseball.
Pitches are thrown underhand, with the ball released while the wrist is passing the side of the body.
Baseball and Softball
Baseball featured several times on the Olympic programme as a demonstration sport before being included as a medal event at the Olympic Games Barcelona 1992.
Cuba won the gold medal on the sport’s competitive debut and three times in total before it was removed from the programme following the Olympic Games Beijing 2008.
Softball was introduced at the Olympic Games Atlanta 1996 as a women-only medal sport, with the United States winning the sport’s inaugural gold medal.
They won the subsequent two titles and enjoyed a 22-game winning streak from September 2000 before they were beaten by Japan in the final in 2008.
Japan chose to reinstate softball and baseball, both of which are hugely popular there.
Both competitions will feature six teams and will be played at Fukushima’s Azuma Stadium before moving on to Yokohama Stadium.