A dock refers to an area of water between two piers or alongside a pier (a platform built out from the shore into the water and supported by piles). It is used for recreational and commercial activities. Marina docks, boat docks and floating docks are among the different types of docks. Recreational types include swim floats and fishing piers. Other categories include marina and boat launch docks. The docks are made of either aluminum frames or wooden frames.

A maritime dock is a chamber like structure used for building or repairing ships. It is also available for boarding and off-loading commercial ships and ferries. A dockyard, the place that repairs and builds ships, includes one or more docks, with other structures. The structure where ships come to be serviced is known as a "dry dock' that can be emptied of water allowing all parts of the boat to be maintained and repaired.

The process of dry-docking a ship starts with building supports, called "blocking," that are concrete, steel or wooden posts. Conforming to the shape of the hull, the posts help to keep the ship upright while the water is drained from the dry dock. Tugboats, used to maneuver, help the ship to enter the dry dock.

Dry docks are usually free floating structures. Graving docks are types of dry docks that can be carved into the shoreline. Floating dry docks, prominent during World War II, were used to set up maintenance facilities in remote locations. Joining several of these docks together can accommodate long ships.

Docks have numerous disadvantages. Prominent among these are the harmful effects on the environment. The construction of a dock is not conducive to aquatic habitat. During its construction, marsh and underwater grasses may be trampled or displaced. This will result in altering critical habitats for marine life. Moreover, the construction diminishes important wetland functions such as flood storage, pollutant uptake, and erosion control.