An F-duct is an aerodynamic device used in formula racing, particularly in Formula 1. It involves a channel that directs airflow from the rear of the car to the front, effectively increasing downforce when needed, particularly during high-speed straight sections. This system can enhance the car's performance by improving grip and stability, allowing for faster cornering. However, the use of F-ducts has been controversial and subject to regulation, as teams seek advantages in design and performance.