Elastic waves are disturbances that travel through elastic materials, such as solids, liquids, and gases. These waves occur when a material is deformed and then returns to its original shape, creating a transfer of energy. Common examples include sound waves in air and seismic waves generated by earthquakes. There are two main types of elastic waves: P-waves (primary waves) and S-waves (secondary waves). P-waves are compressional waves that move in the same direction as the wave, while S-waves are shear waves that move perpendicular to the wave direction. Both types are essential for understanding seismology and the behavior of materials under stress.