Barcode reader

Barcodes are a series of black and white lines which are used to store some numerical value. The number, shown at the bottom of the bardcode, is unique to that product which allows the devices reading the bardcode to look up data about it from a database.

The thickness of the lines represent the value. The longer lines at the start and end of the barcode allow the reader to know where the start and end of the code is. This means that the reader can read the code from any angle as it will always be able to tell which way around it is.

The reader will pass a laser across the barcode. The laser will reflect differently on the white and black lines which allows it to work out the value if each line. Sometimes the reader will make a mistake. In order to catch these errors barcodes always contain a check digit. Read the section on check digits for more information.