Port

A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as Hamburg, Manchester and Duluth; these access the sea via rivers or canals. Because of their roles as ports of entry for immigrants as well as soldiers in wartime, many port cities have experienced dramatic multi-ethnic and multicultural changes throughout their histories.

Ports are extremely important to the global economy; 70% of global merchandise trade by value passes through a port. For this reason, ports are also often densely populated settlements that provide the labor for processing and handling goods and related services for the ports. Today by far the greatest growth in port development is in Asia, the continent with some of the world's largest and busiest ports, such as Singapore and the Chinese ports of Shanghai and Ningbo-Zhoushan. As of 2020, the busiest passenger port in Europe is the Port of Helsinki in Finland. Nevertheless, countless smaller ports do exist that may only serve their local tourism or fishing industries.

Ports can have a wide environmental impact on local ecologies and waterways, most importantly water quality, which can be caused by dredging, spills and other pollution. Ports are heavily affected by changing environmental factors caused by climate change as most port infrastructure is extremely vulnerable to sea level rise and coastal flooding. Internationally, global ports are beginning to identify ways to improve coastal management practices and integrate climate change adaptation practices into their construction.

Wherever ancient civilisations engaged in maritime trade, they tended to develop sea ports. One of the world's oldest known artificial harbors is at Wadi al-Jarf on the Red Sea. Along with the finding of harbor structures, ancient anchors have also been found.

Other ancient ports include Guangzhou during Qin dynasty China and Canopus, the principal Egyptian port for Greek trade before the foundation of Alexandria. In Ancient Greece, Athens' port of Piraeus was the base for the Athenian fleet which played a crucial role in the Battle of Salamis against the Persians in 480 BCE. In ancient India from 3700 BCE, Lothal was a prominent city of the Indus valley civilisation, located in the Bhal region of the modern state of Gujarāt. Ostia Antica was the port of ancient Rome with Portus established by Claudius and enlarged by Trajan to supplement the nearby port of Ostia. In Japan, during the Edo period, the island of Dejima was the only port open for trade with Europe and received only a single Dutch ship per year, whereas Osaka was the largest domestic port and the main trade hub for rice.

Ostia Antica (lit. 'Ancient Ostia') is an ancient Roman city and the port of Rome located at the mouth of the Tiber. It is near modern Ostia, 25 km (16 mi) southwest of Rome. Due to silting and the invasion of sand, the site now lies 3 km (2 mi) from the sea. The name Ostia (the plural of ostium) derives from Latin os 'mouth'. Ostia is now a large archaeological site noted for the excellent preservation of its ancient buildings, magnificent frescoes and impressive mosaics. The city's decline after antiquity led to harbor deterioration, marshy conditions, and reduced population. Sand dunes covering the site aided its preservation. Its remains provide insights into a city of commercial importance. As in Pompeii, Ostia's ruins provide details about Roman urbanism that are not accessible within the city of Rome itself. Post-classical Swahili kingdoms are known to have had trade port islands and trade routes with the Islamic world and Asia. They were described by Greek historians as "metropolises". Famous African trade ports such as Mombasa, Zanzibar, Mogadishu and Kilwa were known to Chinese sailors such as Zheng He and medieval Islamic historians such as the Berber Islamic voyager Abu Abdullah ibn Battuta.

Many of these ancient sites no longer exist or function as modern ports. Even in more recent times, ports sometimes fall out of use. Rye, East Sussex, was an important English port in the Middle Ages, but the coastline changed and it is now 2 miles (3.2 km) from the sea, while the ports of Ravenspurn and Dunwich have been lost to coastal erosion.

The maritime republics (Italian: repubbliche marinare), also called merchant republics (Italian: repubbliche mercantili), were Italian thalassocratic port cities which, starting from the Middle Ages, enjoyed political autonomy and economic prosperity brought about by their maritime activities. The term, coined during the 19th century, generally refers to four Italian cities, whose coats of arms have been shown since 1947 on the flags of the Italian Navy and the Italian Merchant Navy: Amalfi, Genoa, Pisa, and Venice. In addition to the four best known cities, Ancona, Gaeta, Noli, and, in Dalmatia, Ragusa, are also considered maritime republics; in certain historical periods, they had no secondary importance compared to some of the better known cities.