Buoyancy is the upward force that allows objects to float in a fluid, such as water. This force occurs because the fluid exerts pressure on the submerged part of the object, creating a difference in pressure between the top and bottom. If the buoyant force is greater than the weight of the object, it will float; if not, it will sink. The principle of buoyancy was discovered by the ancient Greek scientist Archimedes. He stated that an object submerged in a fluid displaces a volume of fluid equal to its own weight. This principle helps explain why ships and boats can float despite being made of heavy materials.