Mail order is the buying of goods or services by mail delivery. The buyer places an order for the desired products with the merchant through some remote method such as through a telephone call or web site. Then, the products are delivered to the customer. The products are typically delivered directly to an address supplied by the customer, such as a home address, but occasionally the orders are delivered to a nearby retail location for the customer to pick up. Some merchants also allow the goods to be shipped directly to a third party consumer, which is an effective way to send a gift to an out-of-town recipient.

A card not present transaction (CNP, MO/TO, Mail Order / Telephone Order, MOTOEC) is a payment card transaction made where the cardholder does not or cannot physically present the card for a merchant's visual examination at the time that an order is given and payment effected, such as for mail-order transactions by mail or fax, or over the telephone or Internet.