Ratchet straps are tie-down straps that have various uses, generally involving the holding down of equipment or cargo when it is being transported. They can be used for jobs like securing loads to vehicles or keeping construction materials in place. 

Also known as tie-down straps, lorry straps, lashing straps or cargo straps, simply put, they are durable webbing that has been equipped with appropriate hardware for tying things down safely and securely.