The three types of seismic waves
Seismic waves are waves of energy that travel through Earth's layers produced by earthquakes or other things related to earthquakes. Seismology is the study of earthquakes and seismic waves. Scientists who study seismic waves are called seismologists. Seismometers are instruments that measure motions of the ground, which include seismic waves and other things generated by earthquakes, etc. Primary and Secondary Waves are known as the body waves.
Primary waves, or P waves, are a seismic body wave that shakes the ground back and forth, in the same and opposite direction as the direction the wave is moving. It is the first wave to arrive at a seismic station (For example a seismograph). Primary Waves are the fastest type of seismic waves. These waves can move through solid rock and fluids. It pushes and pulls rock it moves through like sound waves push and pull the air.
Secondary waves, also known as S waves, are one of the two main types of elastic body waves. These waves are slower than P waves, so it arrives later at a seismic station because they travel slower in rock. This is how secondary waves got their names. Unlike the P waves, S waves can't travel through the molten outer core of the Earth. S waves have a swaying, rolling motion that shakes the ground back and forth, unlike P waves who move backwards and forwards.
Surface waves, unlike P and S waves, don't penetrate the interior of the Earth. Surface waves always arrive last at seismic stations, and are slower than the body waves. They got their name because, well, they travel on the surface! However, they are the most destructive of the seismic waves because of their low frequency that makes them more likely than body waves to stimulate resonance in buildings. The two types of surface waves are Rayleigh waves and and Love waves. Rayleigh waves are surface waves that travel as ripples similar to to those on the surface of water. Love waves are surface waves that cause horizontal shearing of the ground, and travel slower than Rayleigh waves.