[list][*]The simulation represents a longitudinal wave traveling along a spring. The grey bands represent the coils of the spring.[/*][*]As the piston moves to the right it compresses the coils in front of it. As it moves to the left it stretches the coils. [/*][*]The compressions and rarefactions move along the spring as a wave.[/*][*]The blue dots show the position of the greatest compression as the wave moves along the spring.[/*][/list]