A force is any influence that causes an object to change its movement, direction, or shape. Forces can make an object begin moving, change speed or direction of motion, or cause a flexible object to deform. There are two main types of forces: contact forces, which act between objects in direct contact, and non-contact forces, which act over a distance. Contact forces include normal forces, friction, and tension. Non-contact forces include gravitational, electric, and magnetic forces. Newton's laws of motion describe how forces cause motion or changes in motion.