A hot-wire anemometer is a device used to measure the speed of fluid flow, typically air. 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 cooling effect allows the device to provide accurate measurements of airflow. Hot-wire anemometers are commonly used in various applications, including aerodynamics, HVAC systems, and environmental monitoring. They are valued for their sensitivity and ability to measure low flow velocities, making them useful in both laboratory and field settings.