Pound-force (lbf) is a unit of force used in the United States customary and British imperial systems. It measures the force required to accelerate a mass of one pound at a rate of one foot per second squared. Essentially, it quantifies how much push or pull is needed to move an object. In practical terms, Pound-force is commonly used in engineering and physics to describe forces acting on structures or materials. For example, when calculating the load on a beam, engineers might express the force in pounds-force to ensure safety and stability in their designs.