third party material definition
In commerce, a  third-party source  means a supplier (or service provider) who is not directly controlled by either the seller (first party) or the customer / buyer (second party) in a business transaction.he third party is considered independent from the other two, even if hired by them, because not all control is vested in that connection. There can be multiple third-party sources with respect to a given transaction, between the first and second parties.