A tractor-trailer is a large vehicle combination commonly used for transporting goods over long distances. It consists of two main parts: the tractor, which is the front part that contains the engine and driver's cab, and the trailer, which is the rear part that carries the cargo. This setup allows for efficient movement of heavy loads on highways and roads. Tractor-trailers are often seen on highways and are essential for the logistics industry, helping to deliver products to stores and businesses. They can vary in size and capacity, depending on the type of cargo being transported, and are typically operated by professional drivers known as truckers.