A piezometer is a device used to measure the pressure of groundwater or the level of water in a well. It typically consists of a tube that is open at the bottom and closed at the top, allowing water to rise inside the tube to a height that reflects the pressure of the surrounding water. This measurement helps in understanding groundwater flow and aquifer conditions. Piezometers are commonly used in fields like hydrology, geotechnical engineering, and environmental monitoring. They can be installed in various locations, such as wells or boreholes, to provide valuable data for managing water resources and assessing soil stability.