Barcode
Consists of a series of thin and thick black lines that when placed in defined patterns represent a numeric or alphabetic character. Various different symbologies identify the defined patterns. Barcodes can be one dimensional -- like the ones found on retail packages or two dimensional (known as 2D). 2D barcodes, which consist of a matrix of black and white blocks can contain large amounts of information. The most popular is PDF-417, developed by Symbol Technologies.