A hot-wire anemometer is a device used to measure the speed of air or fluid flow. It consists of a thin wire heated by an electric current. As air flows over the wire, it cools down, and the amount of cooling is related to the flow speed. This change in temperature is used to calculate the velocity of the fluid. These instruments are commonly used in various applications, including aerodynamics, HVAC systems, and environmental monitoring. Hot-wire anemometers are valued for their sensitivity and ability to measure low flow rates accurately, making them useful in both laboratory and field settings.