Two-dimensional symbologies have been around for a while but they did not reach the broad public until the last few years. Examples include the “bull's eye” code that appears in all United Parcel Service packages and the two-dimensional bar code PDF417 that appears in driver's licenses in several states, metered postage, and identity documents. The paper covers the basic principles of the design of such codes, problems associated with their reading, and examples of applications. It will also review how such symbologies related to OCR-based document reading and how the technologies can supplement each other.