After the ball left your hand, gravity was the only force acting on the ball. Gravity continually slowed the ball by pulling downward on it until the ball stopped and began to move back toward the earth.

If a string were attached to the ball, the same motion would be seen. The ball would reach a high point and then fall back down. However, the string would control the direction of motion and cause the ball to move in an arc. The ball and the string make up what is called a pendulum. A common example of a pendulum is a swing.