A harbor, harbour or a haven is a place to take shelter or refuge from difficult weather or any other danger. Usually it is used as a safe place for ships, boats or barges. Sometimes harbors are confused with ports or docks. A port is a safe place for vessels and it is equipped for loading and unloading ships, while a harbor is a haven for vessels but does not necessarily have onshore facilities. The harbors can be natural or man- made.

1. Natural harbour – A natural harbor is a such an arrangement where a part of a body of water is protected and is deep enough to allow ships to anchor. The ships can stay protected or hidden from most sides. The waves are also much calmer  inside the harbor. Some examples are New York City harbor in the United States,  Sydney Harbor in Australia and Pearl Harbor in Hawaii.
2. Man-made harbour – Man made or artificial harbors are built for use as ports. All artificial harbors are ports because they are designed to be one. The largest artificially created harbor is Jebel Ali in Dubai. Some other examples are Port of Long Beach, California; and Port of Los Angeles in San Pedro, California.
3. Ice free harbour – There is another category of harbours and that is Ice free harbors. For places near the south and the north pole where there is ice all year round, it is very important for the harbours to be ice free. Some examples of ice free harbors are Murmansk, Russia;  St. Petersburg, Russia; Hammerfest, Norway; Vardø, Norway; and Prince Rupert Harbour, Canada. So you see mostly in Russia, Norway and Canada, nearer to the north pole.

Some world famous harbours:

• World’s largest harbor – Poole Harbour is a large natural harbour in Dorset, southern England.
• World’s smallest harbour – Depoe Bay is a city in Lincoln County, Oregon, United States.
• World’s busiest port – Port of Shanghai in China is the busiest port.
• World’s largest port – Port of Shanghai in China is the largest port in size.
• World’s most famous port – Pearl harbour in Hawaii, for its WW II attack.