Multimodal transport is the transportation of goods under a single contract, but performed with at least two different modes of transport; the carrier is liable for the entire carriage, even though it is performed by several different modes of transport. 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. The carrier responsible for the entire carriage is referred to as a multimodal transport operator, or MTO.