A butterfly valve is a flow control valve used to regulate the movement of fluid through a pipeline. It is named after the disc, which resembles butterfly wings and rotates on a shaft inside the valve body to open or close the flow passage.

Butterfly valves are highly versatile and are widely used in industries such as water treatment, HVAC systems, chemical processing, food and beverage, and oil and gas. They are particularly suitable for applications that require quick operation and minimal pressure drop.