A pier is a raise walkway over water, supported by widely spread piles or pillars. The lighter structure of a pier allows tides and currents to flow almost unhindered, whereas the more solid foundations of a quay or the closely-spaced piles of a wharf can act as breakwaters, and are consequently more liable to silting. Piers can range in size and complexity from a simple lightweight wooden structure to major structures extended over a mile out to sea. Piers are the same as docks, which would be found in lakes or on rivers, it is the standard terminology used.