A freight broker acts as an intermediary between a shipper and a freight service provider, such as a trucking company or a railroad. The broker's role is to help match the shipping needs of the shipper with the capabilities of the freight service provider.

Freight brokers typically have a network of carrier contacts, including trucking companies, railroads, and ocean carriers, that they can use to find the right carrier for a given shipment. They also handle many of the logistics and administrative details of the shipment, such as arranging for transportation, scheduling pickups and deliveries, and tracking the shipment in transit.

As you mentioned, freight brokers can specialize in certain types of freight, such as oversize, equipment hauling, bulk tanker, auto, or other specialized types of transportation. This can be useful for shippers because they can work with a broker that has expertise in the specific type of freight they need to ship, which can help ensure that the shipment is handled properly and delivered on time.

Freight brokers also play an important role in the transportation industry by providing access to capacity for shippers and helping to balance supply and demand for different types of shipping services. They also provide valuable services such as tracking, documentations and insurance that shippers may need.