A barometer is the device used to measure atmospheric pressure. Barometers play a crucial role in meteorology and are essential for weather prediction and understanding atmospheric conditions. There are two primary types of barometers: mercury barometers and aneroid barometers. Mercury barometers use mercury in a glass tube, where the height of the mercury column indicates atmospheric pressure. Aneroid barometers, on the other hand, use a sealed metal chamber that expands or contracts with changes in pressure, which is translated into a measurement. Accurate atmospheric pressure readings are vital for forecasting weather patterns, predicting storms, and understanding changes in the environment.