Seismic waves are vibrations that travel through the Earth, usually caused by events like earthquakes or volcanic eruptions. These waves help scientists understand the Earth's structure and can be detected by instruments called seismometers. There are two main types of seismic waves: P-waves, which are fast and compress the ground, and S-waves, which are slower and move the ground up and down. When an earthquake occurs, it generates seismic waves that spread out in all directions. By studying these waves, researchers can learn about the Earth's interior, including the mantle and core. This information is crucial for understanding geological processes and predicting future seismic activity.