A pier is a structure constructed over the surface of a body of water to support a pathway or standing room with close access to the water or to objects in it, especially boats. It should generally lie close to the surface, and is not designed to form a pathway across the water (like a bridge) but rather to bring persons or objects close to the water.

Piers are usually connected to the shore, but may also be detached from shore. Normally their foundations are in the floor of the body of water, but they can also float or be cantilevered or suspended from land-based anchor points. They may or may not have barriers around their edges. Piers can support foot traffic and/or vehicle traffic.

The pathway or platform brings users close to the water. Its supports can be fixed, floating, cantilevered, or suspended without changing that access purpose into a crossing between opposite shores.