According to the Negotiable Instruments Act, 1881, a 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, or to the order of a certain person or to the bearer of the instrument. A bill of exchange has many features such as, it is in writing, the order to make payment is unconditional, must be payable to bearer, has grace period, must be stamped as per the requirement of law, etc. Crossing is not necessary for a bill of exchange.