Barcode

A barcode or bar code is a method of representing data in a visual, machine-readable symbolic form. Initially, barcodes represented data by varying the widths, spacings and sizes of parallel lines. These barcodes, commonly referred to as linear or one-dimensional (1D), can be scanned by optical scanners known as barcode readers. Later, two-dimensional (2D) variants were developed, using rectangles... (Wikipedia)