Rubber is made from long-chain polymer molecules. When you hold the ball in your hand, these long molecules are tangled together like a ball of molecular spaghetti. During a collision, these molecules stretch but only for a moment. Atomic motions within the rubber molecules then return them toward their original, tangled shape. Much of the energy of the ball's downward motion becomes upward motion as the ball returns to its original shape and bounces into the air. The energy in the ball that isn't converted into motion becomes warmth. (You can verify this the next time you play a game of racquetball. At the end of the game, the ball will be warmer than when you started.) For the complete story http://www.exploratorium.edu/sports/ball_bounces/ballbounces2.html The more pressure a basketball has inside it, the less its surface dents during a bounce and the more of its original energy it stores in the compressed air. Air stores and returns energy relatively efficiently during a rapid bounce, so the pressurized ball bounces high. But an underinflated ball dents deeply and its skin flexes inefficiently. Much of the ball's original energy is wasted in heating the bending skin and it doesn't bounce very high. In general, the higher the internal pressure in the ball, the better it will bounce. Side Notes - A bowling ball bounces well from a hard surface such as cement. When it hits a softer surface such as wood, the wood receives much of its energy and wastes that energy as thermal energy. The golf ball bounces from the golf club and the more bouncy the golf ball is, the faster and farther it will travel.

A ball bounces because the force(s) that propelled it in its direction caused it to deform elastically. The energy given to the ball is conserved in various forms: some of it is "lost" to friction and heat during the impact and some of it is "retained" in the ball as it regains its previous shape and "jumps" off the surface with the remaining energy. The opposite of this, would be inelastic collissions. These are the ones where after the impact, the original shape is no longer retained. The energy is dispersed into deforming the surface(s) which do not go back to its original shape. It's like throwing a tennis ball into sand... it may bounce a little but not as much as if you had thrown it on a hardwood floor.

Elastic deformation and return

Newton, Sir Isaac, a mathematician and physicist stated that "A collision is an interaction between two objects which have made contact (usually) with each other. As in any interaction, a collision results in a force being applied to the two colliding objects". Such collisions are governed by Newton's laws of motion. As I understand this, regardless of what two object collide, the force that is generated when the two objects collide, is then equalled by the same force pushing them apart. Soon after gravity comes into play and (in you're question) the ball will continue to bounce. This link explains things far better than I can. http://www.newton.cam.ac.uk/newtlife.html

A ball bounces because there are springs inside them - joke. Actually everything bounces. How high the trip upwards depends on how hard the trip down was. "Every action has an equal but opposite reaction" Newton. And when you factor in all the present constants and variables (consistency of the "ball", the surface of which it is bouncing off of, the force and speed of which it is being pushed, the environment, blah blah blah) you could understand why a basketball bounces much better than a bowling ball... I have no clue where to even begin to calculate any of this so...

because it hates touching things

A ball bounces due to the concept of newons law, "For every action there is an equal and opposite reaction." and so, the momentum of the ball hits the grouns and the transfer on kinetic energy, forces the ball back at you at almost the same force