Pertinent sections from the NCAA Basketball equipment requirements for the 2010 / 2011 year... Specifically:
a game in which two teams of five players each compete to throw a ball through a hoop.
well the size is roughly around 18 inches but it it depends on what type of net it is.
AIRBALL
goal? as in hoop? To stand straight and 10" tall, and be round so the ball can go in it.
basketball basketball hoop extra: basketball hoop net backboard boundary lines uniforms refs chairs drink whistles clock/timer/point keeper
The net's point is to make hte ball go straight down from the hoop.
Bucket
A basketball net is a type of open structure, typically made of nylon or chain, designed to catch and hold the basketball when a shot is made through the hoop.
10 feet from the floor to the top of the goal (hoop).
An official, NBA-approved basketball net may be anywhere between 15" to 18" long. Obviously, it must also go around the rim of the hoop. An official basketball hoop is 18" in diameter; thus, the net must also be 18" in diameter at its widest point.
The first net wasn't actually a net. The first basketball hoop was actually a wooden crate with no top or bottom in it and it was nailed high on a post.
10 Feet from the ground to the top of the rim.