The Negotiable Instruments Act 1881 governs the provisions for bills of exchange. According to Section 5 of this act, the bill of exchange is defined as “An instrument in writing containing an unconditional order signed by the maker, directing a certain person to pay a certain sum of money only to the order of the certain person or to the bearer of the instrument.” When such order is accepted in writing it becomes a valid bill of exchange. Learn more about Bills of Exchange here.