Idea is a little hazy. It is a sport, but an odd one.
Okay, I only learned to play this today, so if I get some of the rules wrong, or omit them, don't downvote me, don't nuke this, just /msg me, and I'll change it. On the other hand though, I can't imagine anyone else in the world would play such a joke of a sport.
Korfball is a mixed team sport much like netball, with four boys and four girls to a team. It is played on a rectangular court, with one basket at either end. There is no backboard, as basketball players might expect, just a woven net on a pole, about 12 feet up. One ball is used, and this visually resembles a football (soccer ball, dammit!), but is a bit smaller, and softer. Passes are like basketball, but netball movement rules apply - only if you don't have the ball.
Now here's where it gets wierd. The court is in two halves. Figures. But you are not normally allowed to change halves. So you are designated an attacker or defender, and so must do your job. Of course, passes can occur across the half-way line, but no movement. Anyone who crosses the half is guilty of a foul, for which the penalty is loss of possession. However, after two goals are scored, the teams change ends. So you will spend two goals as an attacker, and two as a defender, and so on.
Goals are much like in netball: simply throw the ball into the net, with a reward of one point. However, if you were marked when you shot (just by proximity - it's a non-contact sport), the goal is disallowed, and possession is conceded. However, marking can only be by someone of the same sex - boys do not mark girls, and vice versa. Shame.
If anyone knows how this game originated, please /msg me as I would love to know. Thanks.