A vane, or indicator, is a device used to show the direction of wind or fluid flow. It typically consists of a flat surface that pivots on a central point, allowing it to align with the wind direction. Vane indicators are commonly found in weather stations, boats, and aircraft, providing essential information for navigation and meteorology. In addition to wind direction, vanes can also be used in various engineering applications, such as in turbines and pumps. They help monitor performance and efficiency by indicating the flow direction of liquids or gases, ensuring optimal operation in different systems.