Barcodes are simplified symbols of codable information that can be read by computer and machines like computer. To define technically, collectivity of black lines in different thickness composed side by side. 

What is a Global Trade Item Number (GTIN)? 

Trade Item is a good or service that is ordered in the Supply Chain and distributed, change places or bought. Because of this all the further information of this trade item is needed beginning from the price. GTIN is a genuine (non-repeating) worldwide descriptive number put on the barcode of a trade item. GTIN serve as a key providing access to the item information in the database and used in ADC (Automatic Data Capture) practices. 

The firm that wants to sell their products retailed applies TOBB-GS1 to Turkey and a 7, 8 or 9 digited GS1 Firm Prefix is allocated according to the necessity. The firm numbers their products sequentially starting from 00001 if the prefix is 7 digited, 0001 if the prefix is 8 digited and 001 if the prefix is 9 digited. These product numbers manufactured by the firm is added to the GS] prefix of the firm and the first 12 digits of a GTIN considered as composed. The 13th and the last digit of the GTIN is considered as the control digit and it's calculated by the barcode writer automatically.