2D codes include multi-row bar codes, matrix codes and composite codes all of which have been effectively used in a number of applications. They are particularly effective for small item marking. Multi-row bar codes feature structured rows capable of containing over two thousand characters in some cases. They also include features to support very powerful error detection and correction capabilities so that even damaged symbols can be read. They are both complementary to and an alternative to linear bar codes. Composites feature two symbols printed close to each other (with fixed relative positions) and contain linked data. Typically, one component is a linear symbol and the other either a multi-row or a matrix symbol.

• well-founded read-only optical technology
• printable by similar techniques to linear barcodes
• variety of labels available to suit a range of applications and user environments
• readable by laser scan technology and image capture systems

• well-founded read-only optical technology
• printable by similar techniques to barcodes
• variety of symbol forming techniques (printing, piercing metal, impressing)
• error detection and correction capabilities essential
• an imaging device is needed to read the code.

2D codes are increasingly being used for marketing and promotional purposes.  Pepsi have recently put 2D codes on their cans in the UK.  These codes contain a URL to Pepsi's website.  When scanned by mobile phones, the phone's browser takes the user to the website where he or she can download ringtones, play games and do various other things.

The codes are also creeping in to mainstream entertainment.  Watch this clip from the American crime programme, CSI, to get a brief summary of 2D codes.

For more information, see how the technology is applied in a range of applications from the links below

• Blood matching with 2D codes
• 2D codes for bank cards