GTIN DEFINITION : INFORMATION
GTIN describes a family of GS1 (EAN.UCC) global data structures that employ 14 digits and can be encoded into various types of data carriers. Currently, GTIN is used exclusively within bar codes, but it could also be used in other data carriers such as radio frequency identification (RFID). The GTIN is only a term and does not impact any existing standards, nor does it place any additional requirements on scanning hardware. For North American companies, the UPC is an existing form of the GTIN. 
The family of data structures (not symbologies) comprising GTIN include:
GTIN-12 (UPC-A): this is a 12-digit number used primarily in North America
GTIN-8 (EAN/UCC-8): this is an 8-digit number used predominately outside of North America
GTIN-13 (EAN/UCC-13): this is a 13-digit number used predominately outside of North America
GTIN-14 (EAN/UCC-14 or ITF-14): this is a 14-digit number used to identify trade items at various packaging levels.