Multimodal transport (also known as combined transport) is the transportation of goods under a single contract, but performed with at least two different modes of transport; the carrier is liable (in a legal sense) for the entire carriage, even though it is performed by several different modes of transport (by rail, sea and road, for example). The carrier does not have to possess all the means of transport, and in practice usually does not; the carriage is often performed by sub-carriers (referred to in legal language as “actual carriers”). The carrier responsible for the entire carriage is referred to as a multimodal transport operator, or MTO.

United Nations Convention on International Multimodal Transport of Goods (Geneva, 24 May 1980) (which will only enter into force 12 months after 30 countries ratify; as of May 2019, only 6 countries have ratified the treaty) defines multimodal transport as follows: “‘International multimodal transport’ means the carriage of goods by at least two different modes of transport on the basis of a multimodal transport contract from a place in one country at which the goods are taken in charge by the multimodal transport operator to a place designated for delivery situated in a different country”.