Hydrostatics is the study of how liquids, like water, interact with the things around them. When a liquid like water is put into an object it will try to fill up every space in the object. But when the object has certain shapes and boundaries, like a water bottle, it can't fill all of the space. The water will push against the walls and this is called hydrostatic pressure. Hydrostatic pressure helps us figure out how much force the water is pushing with so engineers can design things that use the force of water, like boats and pools.