International trade is based on the notion of exchange which involves what is being traded, the partners involved as well as the transactional environment in which trade takes place, namely custom procedures (tariff and non-tariff barriers). Commonly, international trade is seen as a series of commercial transactions between trade partners that tracks the value of what is being traded as well as the concerned nature of goods (such as standard international trade classification). Its extent, either in value or volume, is an abstract expression of the quantity of goods being exchanged as they do not represent the actual physical flows supporting trade.The physical realization of international trade requires a transport chain which is a series of logistical activities that organize modes and terminals, such as railway, maritime and road transportation systems, and thus the continuity along the supply chain through a set of stages, the most common being:
