A basketball is a spherical ball used in basketball games. Basketballs usually range in size from very small promotional items that are only a few inches (some centimeters) in diameter to extra large balls nearly 2 feet (60 cm) in diameter used in training exercises. For example, a youth basketball could be 27 inches (69 cm) in circumference, while a National Collegiate Athletic Association (NCAA) men's ball would be a maximum of 30 inches (76 cm) and an NCAA women's ball would be a maximum of 29 inches (74 cm).

The standard for a basketball in the National Basketball Association (NBA) is 29.5 inches (75 cm) in circumference and for the Women's National Basketball Association (WNBA), a maximum circumference of 28.5 inches (72 cm). High school and junior leagues normally use NCAA, NBA or WNBA sized balls.

The ball used for all competitions (men's, women's, and mixed) in the formal halfcourt game of 3x3 combines characteristics of the size 580–620 g for men and 510–550 g for women.

More Info: en.wikipedia.org