A seismograph is an instrument used to detect and record the vibrations caused by earthquakes and other seismic activities. It consists of a mass suspended on a spring, which remains still while the ground moves during an earthquake. The movement of the mass is recorded on a rotating drum or digital device, creating a visual representation of the seismic waves. Seismographs are essential for understanding the Earth's internal structure and for monitoring tectonic activity. They help scientists, known as seismologists, analyze the strength, duration, and location of earthquakes, contributing to improved safety measures and disaster preparedness in affected areas.