Longitudinal waves are mechanical waves in which the particles of the medium vibrate in a direction parallel to the direction in which the wave is moving. This means that the disturbance or vibration of the medium is in the same direction as the wave propagation. Sound waves are a common example of longitudinal waves, where air particles vibrate back and forth in the same direction as the sound wave is traveling. Other examples of longitudinal waves include seismic waves (waves that travel through the Earth) and pressure waves in fluids.
