Gravity and air are the two most relevant factors that influence the flight of a Frisbee.  Even while flying through the air, Frisbees are still being pulled by gravity.  When the Frisbee is flying, lift and angular momentum take hold of it.  An angle of attack is the angle formed by the tilt of the Frisbee as compared to the ground.  If this angle is positive, the air moving across the top of the Frisbee will go faster compared to the air underneath it.  According to Bernoulli's Principal, the air pressure is lower on the top of the Frisbee than under it.  This difference in pressure causes the Frisbee to rise.  Newton's Third Law also plays a major role in this flight.  For every action, there is an equal and opposite reaction.  The Frisbee forces down while the air forces it up.  Rotation is also important in a flying Frisbee.  A Frisbee would fall if its aerodynamics weren't perfectly centered.  Due to its angular momentum, a spinning Frisbee can keep its orientation for a long time.  The angular momentum is maximized by having the edges of the Frisbee thicker.

So, when did Frisbees come about anyways?  Believe it or not, they started in the 1940s.  Some guy named Fred Morrison was performing some experiments with flying discs.  These antique Frisbees that he was working with were made from metal or plastic. (Plastic was the new material back then.)  The Wham-O Company purchased the rights and molds from him in 1955.  Frisbees really went in style in the 1960s.  A Frisbee competition is even held in California.  It's called the World Frisbee Competition in California.  Frisbees are still popular nowadays because you need not have any skill at all to learn how to throw them correctly.  Hey, the little girl and the woman in the picture above look like they're having fun.

So, how does a Frisbee move about?  Well, this is how...  You decide that you and your friend should go outside to chuck the Frisbee around. Your friend agrees.  You go to the garage and grab a nice, red, Frisbee.  You swing back and you throw the Frisbee correctly.  As the Frisbee leaves your hand, the air in front of the Frisbee splits.  Some airflow goes over and some goes under the Frisbee.  Because the shape of the Frisbee is somewhat like a dome, this allows more air to go over the top than the bottom of it.  When the Frisbee is traveling at high speeds, the air on top of it moves away from the back.  This causes the airflow to speed up.  Since the air on the top is moving faster, it has more kinetic energy.  The bottom has the greatest potential energy pushing it up.  All these things are what allow a Frisbee to take flight.