Magnetic ink character recognition (MICR) is a technology used primarily to identify and process checks. The MICR on a check is the string of characters that appears at the bottom left of the check. It consists of three groups of numbers, including the bank routing number, the customer's account number, and the check number.3

The MICR includes, from left, a nine-character routing number, a 12-character account number, and a four-character check number.