A harbor provides safe anchoring or mooring for ships and may be natural or man-made. It has an entrance but no gates. A dock is dug out and has gates to regulate water levels for mooring ships to exchange cargo or passengers or undergo repairs. A port contains one or more harbors and allows ships to dock and transfer people and goods between land and sea. Harbors have features like entrance channels, berthing basins, breakwaters, piers, wharves and jetties to facilitate ship movement and cargo operations.