What is Bill of Exchange?

Bills of exchange are similar to checks and promissory notes. They can be drawn by individuals or banks and are generally transferable by endorsements. The difference between a promissory note and a bill of exchange is that this product is transferable and can bind one party to pay a third party that was not involved in its creation. If these bills are issued by a bank, they can be referred to as bank drafts. If they are issued by individuals, they can be referred to as trade drafts.

Source: http://www.investopedia.com/terms/b/billofexchange.asp