softball, Game resembling baseball but played on a smaller diamond with a larger ball (12 in. [30.5 cm] in circumference), which is pitched underhand. Since the first standard set of rules was published in the 1920s, the game has been popular as an amateur sport in the U.S., and since the 1960s it has grown considerably in popularity outside of North America. In U.S. high schools and colleges it is a popular women’s sport; a women’s softball competition was added to the Olympic Games in 1996.