A freight broker arranges transportation for a shipper's freight without owning the trucks. When a shipper has a load, the broker finds a carrier with the right equipment on the lane, agrees the pickup and delivery, books the truck and manages the load until it is delivered. The shipper deals with the broker, and the broker deals with the carrier.
Because brokers work with many carriers, they can often find capacity quickly, offer several truck types and cover lanes a single carrier does not run. That makes them useful for one-off loads, peaks, unusual freight and urgent shipments, as well as steady lanes.
ExpeditedFreight.com works this way, booking dedicated trucks from carriers for urgent loads, from Sprinter vans to 53 ft dry vans and flatbeds, with air freight when the road is too slow.