A bill of exchange refers to a written order issued by one party to another, directing the latter to pay a specific amount of money at a predetermined time. It can either be payable upon presentation or upon demand, also known as "at sight". This financial instrument is commonly used in international trade and serves as a form of credit between parties. The bill of exchange is a vital tool for managing cash flow and ensuring timely payments. Its flexibility and convenience make it a popular choice in the world of finance.