A port is a docking place for ships on the coast of the ocean, a river or a lake. Ships dock at ports to load and unload their cargo and passengers.

Ports play a crucial role in transporting goods and raw materials. They are often categorized by their purpose. For example, Ras Tanura, Saudi Arabia, is an oil port. Concarneau, France, is a fishing port. Gibraltar, a territory of Great Britain, is a naval port, used by the military. Nassau, Bahamas, is a cruise ship and tourism port.

Ships usually have more than one port of call, or place where they dock. Before the construction of the Panama Canal, a ship traveling from the American cities of New York, New York, to San Francisco, California, would have dozens of ports of call around the coasts of North and South America. These might include Miami, Florida, United States; Recife, Brazil; Buenos Aires, Argentina; Valparaiso, Chile; and Acapulco, Mexico.

Cargo Ports
Cargo ports are important commercial centers where water transportation and land transportation meet. Many goods, such as cars, oil, iron and steel, are too heavy or unwieldy to be transported across long distances by plane or truck. Trains may transport such goods to a port, where they are loaded onto a ship. Once on the ship, goods travel across the globe.

Some cargo ships are far too large to operate in a crowded port. Tugboats are small, powerful boats that tug large ships behind them. The tugboat can pull the heavier ship into port with greater ease than the ship could manage on its own. Tugboats are familiar sights at many ports.

The port of New Orleans, Louisiana, has been one of the busiest cargo ports in the United States for hundreds of years. This port connects the interior of the United States to the rest of the world through the Mississippi River and the Gulf of Mexico. The Mississippi moves more than 500 million tons of cargo every year. Thousands of ships dock along the Mississippi in New Orleans. Ships from the United States unload goods such as grain and other agricultural products from the Midwest. Ships from Latin America unload coffee and goods such as rubber. Ships from Asia may bring goods like clothing or barrels of oil.

Most cargo ports are warm-water ports. Warm-water ports are ports that remain ice-free all year. Even ports where the water is cold, such as New York or Vancouver, Canada, are warm-water ports. Russia has thousands of miles of coast, and hundreds of ports, along the Arctic Ocean. Almost all of these are cold-water ports. They sometimes remain locked in ice for weeks or even months at a time. Goods cannot be transported in or out of the port when it is blocked by ice. Sailors cannot board or stay in submarines when the vessels are surrounded by ice.

Passenger Ports
Some ports, such as the one in Dover, England, chiefly serve passengers. The port at Dover has been used by people for centuries because it provides the shortest sea crossing between England and Europe, at just over 32 kilometers (20 miles).

Passenger ports have traditionally been centers of communication. Historically, ports brought the latest news, goods and fashion from overseas. People who live and work around busy ports are often familiar with foreign languages and cultures. The port of New York was the gateway to the United States for millions of immigrants from Europe in the 19th and 20th centuries, for instance. Italian, Spanish and Yiddish became familiar languages, while customs from Scandinavia and Russia mixed with Irish traditions.