Barcode is a basic machine-readable code used for marking products. The best known type of barcode is UPC. It consists of linear patterns and a 12-digit string. The first five digits represent the manufacturer’s code, the next five represent the product code, one is used as a number system character while the check digit is used for error detection. This thesis describes its structure and the method of coding and reading data. Of the more advanced codes, QR code is the most important. Its basic structural component is called module. Groups of modules together create patterns that are responsible for various code functions. In addition to its distinctive appearance, the code also stands out for its large storage capacity, error correcting capabilities and easy reading. This thesis briefly explains how does QR code work, as well as some methods for increasing its capacity related to use of color and data compression. There are several types of QR codes with specific features that have allowed them to be applied differently. Among the other codes, in this thesis are listed mCode, Trillcode, HCCB, Ultracode and BeeTagg as some of the more advanced machine-readable codes.