A 2D (two-dimensional) barcode is a graphical image that stores information both horizontally -- as one-dimensional bar codes do -- and vertically. As a result of that construction, 2D codes can store up to 7,089 characters, significantly greater storage than is possible with the 20-character capacity of a unidimensional barcode.

2D barcodes are also known as quick response codes because they enable fast data access. 2D barcodes are often used in conjunction with smart phones. The user simply photographs a 2D barcode with the camera on a phone equipped with a barcode reader. The reader interprets the encoded URL, which directs the browser to the relevant information on a Web site. This capability has made 2D barcodes useful for mobile marketing. Some 2D barcode systems also deliver information in a message for users without Web access.