A hydraulic Seal is a component of a hydraulic system that helps to prevent hydraulic fluid from leaking past moving parts within the system. Hydraulic seals are typically made of durable and flexible material, such as rubber or polyurethane, and are designed to fit tightly around the moving parts they are sealing. There are several types of hydraulic seals, including piston seals, rod seals, wiper seals, and static seals.