Four main interelated dimensions help define the role and function of a port:
- Geography. A port is a site with convenient harbor characteristics (such as a protected bay) that supports a more effective interface between the maritime and land domains than other locations. Although the location of a port does not change, the site can be improved through dredging and land reclamation, which requires substantial capital investments. This allows the port to expand its surface and the amount of traffic it can handle. The situation of a port can also change, as it depends on the market it serves and includes manufacturing and consumption areas.
- Scale. Refers to the scale of the activities performed at the port and also the scale of its market coverage. A port has scale characteristics, including the types of traffic it can handle and the throughput. This is contingent upon the infrastructure (berths) and the superstructure (cranes and yard equipment) linking the port foreland (the ports it is connected to) and the port hinterland (inland market area). With capital investments and management, the operational efficiency of a port can be improved with changes to land, equipment, and management.
- Function. A port adds value to transport and supply chains through its cargo handling. Historically, heavy industrial activities such as steel mills and petrochemical plants had a propensity to be located within or nearby ports. This process is still ongoing and is being complemented by a large array of freight distribution activities. There is a diversity of port functions associated with specialization forms, such as ports involved in minerals, energy, and containers. Large ports tend to be polyfunctional, while smaller ports tend to be monofunctional.
- Governance. A port is a well-defined administrative unit that involves land ownership and jurisdiction (what a port can legally do). The port authority is a common administrative framework for a port, and in many cases, terminal management and operations are leased to private companies. Port authorities usually have the right to spearhead port development projects and secure funding.