A bill of exchange is a financial instrument that is used in international trade to facilitate payment between parties in different countries. It becomes negotiable when it is accepted by the drawee. This means that the drawee (the person who is required to pay the amount specified on the bill of exchange) has agreed to the terms of the bill and has committed to paying the amount owed at a specified date in the future. Once the bill of exchange is accepted, it can be traded or sold to another party, who can then collect payment from the drawee at the specified date. The negotiability of the bill of exchange makes it a useful tool for businesses engaged in international trade, as it allows them to obtain financing or transfer risk to another party.