GTINs are Global Trade Identification Numbers. Hence GTIN refers to any barcode number or product identification number, as used in retail as part of the standard GS1 barcoding and product identification system.

GTINs can be –
GTIN-13 (or EAN-13) – 13 digit numbers normally used on retail products outside the USA
GTIN-12 (or UPC-A) – 12 digit numbers typically used on retail products in the USA
GTIN-14 (or ITF-14) – 14 digit numbers used on cartons for storage & shipping (not sold at retail level). These carton code numbers are based on the GTIN (12 or 13) of the retail product within the carton – so the GTIN-14 can be used to identify what product is in the carton, and also to let the distributor or retailer know how many products are inside the carton.
GTIN-8 – an 8 digit number normally used outside the USA. These small numbers are encoded in small barcodes, and used on small products. However, because they only contain 8 digits, their supply is limited and they are very hard to obtain (& expensive). They are only available directly from GS1.


Example of a GTIN-14 (in ITF-14 Format)