A wharf or quay (pron.: /ˈkiː/, US also /ˈkeɪ/ or /ˈkweɪ/) is a structure on the shore of a harbor where ships may dock to load and unload cargo or passengers. Such a structure includes one or more berths (mooring locations), and may also include piers, warehouses, or other facilities necessary for handling the ships.
A wharf commonly comprises a fixed platform, often on pilings. Commercial ports may have warehouses that serve as interim storage areas, since the typical objective is to unload and reload vessels as quickly as possible. Where capacity is sufficient a single wharf with a single berth constructed along the land adjacent to the water is normally used; where there is a need for more capacity multiple wharves, or perhaps a single large wharf with multiple berths, will instead be constructed, sometimes projecting into the water. A pier, raised over the water rather than within it, is commonly used for cases where the weight or volume of cargos will be low.
Smaller and more modern wharves are sometimes built on flotation devices (pontoons) to keep them at the same level as the ship, even during changing tides.
In everyday parlance the term quay is common in the United Kingdom, Canada, Australia, and many other Commonwealth countries, and the Republic of Ireland, whereas the term wharf is more common in the United States. In some contexts wharfand quay may be used to mean pier, berth, or jetty.