Two-dimensional barcodes are made up of vertical lines because they only carry information horizontally. In these bar codes, information is indicated by the distance between and thickness of lines, which is read by a laser reader. Additionally, two-dimensional barcodes can make use of different layers to communicate larger amounts of information per code.
The second type of barcode commonly known as a 3D barcode is sometimes called a QR code. QR codes are square black and white images that transmit information horizontally as well as vertically. These codes are unique because they do not need a specialized reader, but can be read by lasers, mobile phones and other mobile devices.