A barcode symbol is a machine readable image which conveys data. Barcodes can be divided into three general types: linear, stacked linear, and two-dimensional (or 2D): Linear Barcodes Read Also | What are Aztec prints ? UPC-A The UPC-A (also referred to simply as the UPC) is the standard retail “price code” barcode in the United States. To order UPC barcodes, please visit www.barcode-us.com. UPC-A is strictly numeric; the bars can only represent the digits from 0 to 9. A UPC-A barcode contains 12 digits, along with a quiet (blank) zone on either side, and start, middle, and stop symbols. The middle symbol separates the left side and the right side, which are coded differently. When a digit is used on the left side, the bars are black and the spaces are white, and when it is used on the right side, the colors are reversed. The logic behind doing this is a little complicated, and involves a mathematical property called “parity,” but the effect is to reverse black and white, and to a...