Since the invention of Uniform Product Code bar symbols in 1973, a sector of the public has been fascinated with the meaning behind the pattern of lines. By studying the numbers within a code, it is possible to identify both the country and manufacturer where a product originated. After practicing, you can also decode the barcode symbols into numbers.
Observe that a barcode label is constructed of both white and black lines in four different thicknesses. Refer to the numeric value of each kind of bar when reading a label. A white bar equals 0, the thin black bar equals 1, the medium bar equals 2, the next largest equals 3 and the widest equals 4.
Note that the "101" symbol begins and ends all UPC codes--made up of a thin black line, followed by a white line and another thin black line. In the centre of each UPC code, observe the extra thin black lines extending down between the numbers in an "0101" pattern.
Understand that each of the 6 numbers on either side of the centre has its own 4 line code: 0 (3211), 1 (2221), 2 (2122), 3 (1411), 4 (1132), 5 (1231), 6 (1114), 7 (1312), 8 (1213) and 9 (3112). Notice that on the left, the number patterns always begin with a white line, whereas on the right, the pattern is reversed, starting with a black line. This ensures a check against errors.
Recognise that a 12-digit UPC code doesn't include a country indicator, since all UPC codes originate from the United States or Canada. Understand that European Article Number (EAN) 13-digit barcodes all include a 2-digit country code at the beginning of the label. This indicates where it was registered, although the product may still have been manufactured in another country.
Understand that the first 6 to 10 digits of a UPC barcode indicate the manufacturer. Utilise that knowledge to note that different brands use the same manufacturer to create similar products under different packaging.
Notice that the sum of each numerical code is always 7.