The discus itself is 1.61 kilograms for Varsity/JV boys in high school, and 4 pounds 66 ounces for College throwers. It is, surprisingly enough, a circular object made of hard rubber, metal and plastic, metal and wood, or metal and metal. Rubber discs are used if you are a. poor, b. practicing or c. have a coach who won't let you use good ones for some reason.
The discus throw is one of the oldest sports known to man, it originated out of Greek games. It takes place in a ring slightly larger than that of a shot put, and uses a similar power position. More hip action takes place with the discus. Blocking is the same as in shot put (see my node there), but the throwing arm is held straight out. The disc is gripped with the pads of the fingers, the thumb held near the center. If you held the disc vertical, it should fall straight out. The disc is held in the hand thanks to centrifugal force; the disc is always moving. Rotary motion in discus is translated into lateral motion when you block and throw. The disc should roll off your index finger last, and spin counter-clockwise if you are left handed. Me being left-handed, I was confused the first year I threw as to how it was supposed to come off my hand. It should spin in a direction opposite to the one your arm is going when you release, to be vague.
Some shot putters use a modified discus spin when they throw. The discus spin begins facing the back of the ring with your feet slightly to the right of the rear of the ring if you are right handed, and to the left if you are left handed. Ambidextrous? Well take your pick. Then, you spin on the ball of your off foot (the one not corresponding to the hand with the disc in it), leap across to plant your power foot in the center of the ring, pull your off foot through while you pivot on the ball of your power foot, land in the power position, twist your hips, push off, block, and finally let all of this motion drag your discus arm forward, behind your chest, and finally release before the arm finishes across your body. The rotary motion transfers from the disc to your body, so afterward you should want your feet to change places. This is called a reverse, and only true ninja discus throwers do it.
Sound complicated? It is. You could be the strongest man in the world and know your way around the ring to an average degree, but you'd still get beaten out in the discus throw by someone who really, really knows what he's doing, even if they're scrawny. In order to be a ninja discus thrower, you must grok every aspect of the technique. Strength doesn't have as much to do with success in discus as it does in shot put, which has a technique that is easier to understand and actually requires more strength to pull off well.