A Rayleigh Wave is a type of surface seismic wave that travels along the Earth's surface. It is named after the British scientist Lord Rayleigh, who studied these waves in the 19th century. Rayleigh waves cause both vertical and horizontal ground movement, which can result in significant shaking during an earthquake. These waves typically travel slower than other seismic waves, such as P-waves and S-waves. Rayleigh waves are particularly important in seismology because they can cause extensive damage to structures due to their rolling motion, making them a key focus in earthquake engineering and safety assessments.