An elastic wave is a type of mechanical wave that travels through a medium, such as solids, liquids, or gases, due to the material's ability to deform and return to its original shape. These waves occur when energy is applied to the medium, causing particles to oscillate around their equilibrium positions. There are two main types of elastic waves: longitudinal waves, where particles move parallel to the direction of wave propagation, and transverse waves, where particles move perpendicular to the wave direction. Elastic waves are fundamental in various fields, including seismology, where they help scientists study earthquakes and the Earth's internal structure.