A damper is a device that provides resistance to motion and reduces energy consumption during movement. The use of damping to absorb energy and reduce vibration is not a new technology. Various dampers (or shock absorbers) have already been applied in industries such as aerospace, aviation, military, firearms, and automobiles to reduce vibration and energy. Since the 1970s, people have gradually applied these technologies to structural engineering such as buildings, bridges, and railways, and their development has been very rapid. Especially for hydraulic viscous dampers with a history of more than 50 years, before they were accepted by the structural engineering community in the United States, they went through a long process of extensive experimentation, rigorous review, repeated verification, and especially earthquake testing.

A device that can quickly stop the movable part of the instrument at a stable deflection position. In seismic instruments, dampers are used to absorb the inherent vibration energy of the vibration system, and their damping force is generally proportional to the velocity of the vibration system's motion. There are mainly three types of dampers: liquid dampers, gas dampers, and electromagnetic dampers. Dampers play an important role in compensating for the small friction and air resistance in the pendulum system of the vibration pickup, and improving frequency response.