A barcode (also bar code) is an opticalmachine-readable representation of data. Originally, bar codes represented data in the widths(lines) and the spacing of parallel lines, and may be referred to as linear or 1D (1 dimensional) barcodes or symbologies. They also come in patternsof squares, dots, hexagonsand other geometricpatterns within images termed2D (2 dimensional) matrixcodes or symbologies. Although2D systems use symbolsother than bars,they are generally referred to as barcodesas well.