Read the following paragraph and answer the question:

"A simple pendulum consists of a bob attached to a string. When displaced from its resting position, the bob swings back and forth in a regular, periodic motion. This to-and-fro movement continues, demonstrating the pendulum's characteristic oscillatory behavior. As it swings, the pendulum periodically returns to its mean position, illustrating a predictable pattern of motion.."

Which type of motion does the pendulum exhibit?