Ask two people to hold the ends of the rope. When one person moves an end of the rope up and down sharply, energy moves from that person's hand and travels through the rope. The person at the other end will feel the incoming energy move his or her hand. As the energy passes through the rope, the rope moves up and down, but does not move forward. Scientists call the material in which waves travel the wave medium.
Water is the medium for water waves, and the rope is the medium for rope waves.
Waves cause little overall displacement of their medium unless the disturbances become unusually large. For example, water waves travel horizontally across the surface of the water, but usually almost all the motion of the water itself is vertical. In physics, a field is a region of space in which a particular kind of force can be felt. For example, a magnetic field is a region in which the force of magnetism can be felt. A magnet produces such a field in the space around itself.