What is Transaction / Authorization Code?
Authorization code is the response code from the issuing bank returned to the merchant at the time of authorization. This code is usually a 6 or 7 digit number and is recorded either by the point of sale terminal or software, as well as printed on any receipt or sales draft. If doing a phone or voice authorization, the merchant should record the authorization code for reference. The code serves as proof of authorization.

What Does Authorization Code Mean?
A generic term that refers to a code or password that identifies the user as authorized to purchase, sell or transfer items, or to enter information into a security-protected space. For example, an authorization code would be required for a vendor to process a credit card transaction on behalf of a customer paying for goods.

An authorization code is commonly attached to credit card transactions, not only to signal a merchant that the transaction is approved, but also to help identify the transaction in follow-up examinations, such as disputed transactions.