Sound waves, earthquakes and ocean waves are all examples of mechanical waves. Longitudinal waves, transverse waves and surface waves are the three types of mechanical waves.
Mechanical waves are waves that spread through a solid, liquid or gas material. The speed of the wave depends on what the medium is made of.
Longitudinal waves, such as the P waves during an earthquake, cause the medium they travel through to move parallel to the starting point of the wave. Longitudinal waves are the fastest mechanical wave type. Sound is also considered a longitudinal wave.
Transverse waves, such as the S waves during an earthquake, cause the medium they travel through to move perpendicular to the starting point of the wave. There are two components of a transverse wave. The crest is the highest point on the wave, while the trough is the lowest, and the distance between these two is half a wavelength. An entire wavelength would be from crest to crest or trough to trough. Transverse waves move slightly more slowly than longitudinal waves.
Surface waves, as the name implies, travel along the surface of a medium in both longitudinal and transverse motions. Surface waves can be anything from waves on the ocean or a lake to Rayleigh waves, which move along solid surfaces. Rayleigh waves travel more slowly than S waves and cause the most damage during an earthquake.