Most people today have seen barcode labels. They are printed on nearly every item in a grocery store. These are either UPC or EAN linear barcodes. However, there are over 300 other different types of barcodes. The next most popular linear barcode is Code 39 . Also, there are 2D Barcodes that can store a large amount of information in a smaller space than linear barcode labels.
 

Most linear barcodes are nothing more than "license plates" that identifies an item. The numbers and/or letters stored in the barcode are unique identifiers that, when read, can be used by a computer to look up additional information about the item. The price and description of the item is generally not stored in the barcode. The data is read from the barcode, sent to a computer, and the computer looks up the price and description of the item from the computer's database.
 

Barcodes are read by either scanning a point of light across the symbol or capturing a video image of the symbol and measuring the lengths white spaces and (black bars. The lengths and positions of the spaces and bars are analyzed by a computer program and the data is extracted. The relative widths of both the bars and spaces code the data stored in the barcode. The barcode reader detects these relative widths and decodes the data from the barcode. The difference between Optical Character Recognition or OCR and barcode is OCR reads text not designed to be read by a computer while barcode reads symbols designed to be read by a computer. That makes the software less complex for decoding barcode. Also, most barcode symbologies have built-in error detection to make the decoding almost 100% accurate. 
 

Finally, if the barcode labels in UPC or EAN barcode, it is usually printed during the printing of the product's packaging. Generally, you will have to obtain a barcode film master from a vendor that specializes in this. However, some printing companies can also do the barcode film master.