For the taxonomic method, see DNA barcoding. For a code of conduct for barristers, see Legal ethics. A UPC-A barcode A barcode or bar code is a method of representing data in a visual, machine-readable form. Initially, barcodes represented data by varying the widths, spacings and sizes of parallel lines. These barcodes, now commonly referred to as linear or one-dimensional (1D), can be scanned by