A hinge joint allows movement in a certain spot to take place. This joint is similar to the opening and closing of a door. Some examples of hinge joints are the elbow, knee, ankle and joints between the fingers. 

Hinge joints allow the body parts to bend and straighten.

Ball and socket joints allow twisting and turning movements. In a ball and socket joint, one of the bones has a rounded head which is the ball. The other bone has a cup-like area that is known as the socket. Some of these joints are the shoulder and the hip. The shoulder joint is the most flexible joint in the entire body. It allows movement in any direction.

There are other types of joints in the body. Gliding joints allow two flat bones to slide over each other like in the bones of the foot and wrist. A condyloid joint allows the head to nod and the fingers to bend. The thumbs has a saddle joint that allows enough flexibility for the thumb to touch any other finger.

If you are "double-jointed", it just means that you have extra long ligaments in your joints and can bend them farther than usual.