Global Trade Item Number (GTIN), can be used by a company to uniquely identify all of its trade items, often found near barcodes.

Source: WikiPedia on Global Trade Item Number:

Global Trade Item Number (GTIN) is an identifier for trade items developed by GS1 (comprising among others of the former EAN International and Uniform Code Council).1 Such identifiers are used to look up product information in a database (often by entering the number through a bar code scanner pointed at an actual product) which may belong to a retailer, manufacturer, collector, researcher, or other entity. The uniqueness and universality of the identifier is useful in establishing which product in one database corresponds to which product in another database, especially across organizational boundaries.

GTINs may be 8, 12, 13 or 14 digits long, and each of these 4 numbering structures are constructed in a similar fashion, combining Company Prefix, Item Reference and a calculated Check Digit (GTIN-14 adds another component- the Indicator Digit, which can be 1-8). GTIN-8s will be encoded in an EAN-8 bar code. GTIN-12s may be shown in UPC-A, ITF-14, or GS1-128 bar codes. GTIN-13s may be encoded in EAN-13, ITF-14 or GS1-128 bar codes, and GTIN-14s may be encoded in ITF-14 or GS1-128 bar codes. The choice of bar code will depend on the application; for example, items to be sold at a retail establishment should be marked with EAN-8, EAN-13, UPC-A or UPC-E bar codes.