The main functions of Ports is to supply services to freight (warehousing, transshipment, etc.) and ships (piers, refueling, repairs, etc.). Consequently, it is misleading to consider a port strictly as a maritime terminal since it acts concomitantly as a land terminal where inland traffic originates or ends. Ports are at start cargo-oriented facilities involving a wide array of the acts.The main function of a port is to supply services to freight (warehousing, transshipment, etc.) and ships (piers, refueling, repairs, etc.). Consequently, it is misleading to consider a port strictly as a maritime terminal since it acts concomitantly as a land terminal where inland traffic originates or ends. Ports are at start cargo-oriented facilities involving a wide array of activities related to their management and operations. The cargo base of a port can expand through the intensification of its fundamental hinterland, the expansion of its hinterland to new areas, and the development of transshipment. In addition to significant cargo-related functions, many ports are also involved in other activities such as fishing, ferries, cruises, and recreational activities (e.g. marinas).
Ports are becoming increasingly regional in their dynamics, which represents a new development from their traditional local function, namely as industrial complexes. For instance, the port of Hong Kong owes its wealth to its natural site and its geographical position of a transit harbor for southern China. A similar function is assumed by Shanghai for central China with the Yangtze river system. Singapore, for its part, has been favored by its location at the outlet of the strategic Strait of Malacca and is, therefore, a point of convergence of Southeast Asian transportation. More than 90% of the traffic it handles is strictly transshipments (cargoes moving from on maritime service to another without exiting the port terminal). New York has traditionally acted as the gateway of the North American Midwest through the Hudson / Erie Canal system, a function which Western European ports such as Rotterdam or Antwerp perform with their access to the Rhine system.
A port throughput is linked to a variety of local and regional industrial activities as the largest ports in the world are gateways to massive industrial regions. However, comparing ports on a tonnage basis requires caution as it does not indicate the nature and the value of the cargo. For instance, a mineral port (e.g. iron ore), an energy port (e.g. coal or oil), and a commercial port (containers) could handle a similar tonnage but significantly different value levels. They will also be related to different commodity chains; bulk ports are very different entities than container ports. In terms of the freight they handle, ports can be classified into two categories; monofunctional ports and polyfunctional ports.
Monofunctional ports transit a limited array of commodities, most often dry or liquid bulks (raw materials). The oil ports of the Persian Gulf or the mineral ports of Australia, Africa, and in some measure of Canada are monofunctional ports. They have specialized piers designed to handle specific commodities and where the flows a commonly outbound, implying that they are usually load centers.
Polyfunctional ports are vast harbors where several transshipment and industrial activities are present. They have a variety of specialized and general cargo piers linked to a wide variety of modes that can include containers, bulk cargo, or raw materials.
About commercial 3,700 ports are in operation worldwide, but only less than one hundred ports have global importance. There are about 600 container ports with 200 handling traffic above half a million TEU. Maritime traffic thus has a high level of concentration in a limited number of large ports, a process mainly attributed to maritime access and infrastructure development. Major ports have established themselves as gateways of continental distribution systems and have access to high capacity inland freight distribution corridors, notably rail. Such a position is very difficult to challenge unless a port is facing acute congestion forcing maritime shipping companies to seek alternatives.