The bill of lading (B/L) is three documents in one: a receipt proving the carrier took your goods, the contract of carriage, and a document of title — whoever holds an original controls the cargo. Its air-freight cousin, the air waybill, is not a title document.
Key variants: original B/L (surrendered physically), telex release (surrendered at origin, released electronically), and seaway bill (no title function, for trusted flows).