The semi-trailer is a type of freight transport vehicle that has its own complete frame, wheels, suspension, and braking system. It is fully towed by a tractor via a drawbar and can park independently without requiring support from the tractor. It is characterized by flexible configuration, independent load capacity, easy connection, and great versatility, making it widely used in various scenarios such as internal transportation within factories, logistics and storage, port handling, construction projects, and short-distance distribution.