Most products carry a simple barcode known as the UPC (universal product code)—a line of vertical stripes with a set of numbers printed underneath it (so someone can manually key in the product number if the barcode is misprinted or damaged in the store and won't scan through the barcode reader). There is another kind of barcode that is becoming increasingly common and its stores much more information. It's called a 2D (two-dimensional) barcode) and you sometimes see it on things like self-printed postage stamps.