A Global Trade Item Number ([GTIN](https://www.gs1.org/standards/id-keys/gtin)). GTINs identify trade items, including products and services, using numeric identification codes.
A correct [gtin](https://schema.org/gtin) value should be a valid GTIN, which means that it should be an all-numeric string of either 8, 12, 13 or 14 digits, or a "GS1 Digital Link" URL based on such a string. The numeric component should also have a [valid GS1 check digit](https://www.gs1.org/services/check-digit-calculator) and meet the other rules for valid GTINs. See also [GS1's GTIN Summary](http://www.gs1.org/barcodes/technical/idkeys/gtin) and [Wikipedia](https://en.wikipedia.org/wiki/Global_Trade_Item_Number) for more details. Left-padding of the gtin values is not required or encouraged. The [gtin](https://schema.org/gtin) property generalizes the earlier [gtin8](https://schema.org/gtin8), [gtin12](https://schema.org/gtin12), [gtin13](https://schema.org/gtin13), and [gtin14](https://schema.org/gtin14) properties.
The GS1 [digital link specifications](https://www.gs1.org/standards/Digital-Link/) expresses GTINs as URLs (URIs, IRIs, etc.). Digital Links should be populated into the [hasGS1DigitalLink](https://schema.org/hasGS1DigitalLink) attribute.
Note also that this is a definition for how to include GTINs in Schema.org data, and not a definition of GTINs in general - see the GS1 documentation for authoritative details.
The GTIN-12 code of the product, or the product to which the offer refers. The GTIN-12 is the 12-digit GS1 Identification Key composed of a U.P.C. Company Prefix, Item Reference, and Check Digit used to identify trade items. See [GS1 GTIN Summary](http://www.gs1.org/barcodes/technical/idkeys/gtin) for more details.
The GTIN-13 code of the product, or the product to which the offer refers. This is equivalent to 13-digit ISBN codes and EAN UCC-13. Former 12-digit UPC codes can be converted into a GTIN-13 code by simply adding a preceding zero. See [GS1 GTIN Summary](http://www.gs1.org/barcodes/technical/idkeys/gtin) for more details.
The GTIN-14 code of the product, or the product to which the offer refers. See [GS1 GTIN Summary](http://www.gs1.org/barcodes/technical/idkeys/gtin) for more details.
The GTIN-8 code of the product, or the product to which the offer refers. This code is also known as EAN/UCC-8 or 8-digit EAN. See [GS1 GTIN Summary](http://www.gs1.org/barcodes/technical/idkeys/gtin) for more details.
The identifier property represents any kind of identifier for any kind of [Thing](https://schema.org/Thing), such as ISBNs, GTIN codes, UUIDs etc. Schema.org provides dedicated properties for representing many of these, either as textual strings or as URL (URI) links. See [background notes](https://schema.org/docs/datamodel.html#identifierBg) for more details.
An image of the item. This can be a [URL](https://schema.org/URL) or a fully described [ImageObject](https://schema.org/ImageObject).
This links to a node or nodes indicating the exact quantity of the products included in an [Offer](https://schema.org/Offer) or [ProductCollection](https://schema.org/ProductCollection).
The ISO 3166-1 (ISO 3166-1 alpha-2) or ISO 3166-2 code, the place, or the GeoShape for the geo-political region(s) for which the offer or delivery charge specification is not valid, e.g. a region where the transaction is not allowed.
See also [eligibleRegion](https://schema.org/eligibleRegion).
The current approximate inventory level for the item or items.
A predefined value from OfferItemCondition specifying the condition of the product or service, or the products or services included in the offer. Also used for product return policies to specify the condition of products accepted for returns.
An item being offered (or demanded). The transactional nature of the offer or demand is documented using [businessFunction](https://schema.org/businessFunction), e.g. sell, lease etc. While several common expected types are listed explicitly in this definition, others can be used. Using a second type, such as Product or a subtype of Product, can clarify the nature of the offer.
Indicates a page (or other CreativeWork) for which this thing is the main entity being described. See [background notes](https://schema.org/docs/datamodel.html#mainEntityBackground) for details.
The Manufacturer Part Number (MPN) of the product, or the product to which the offer refers.
The name of the item.
A pointer to the organization or person making the offer.
Indicates a potential Action, which describes an idealized action in which this thing would play an 'object' role.
The offer price of a product, or of a price component when attached to PriceSpecification and its subtypes.
Usage guidelines:
- Use the [priceCurrency](https://schema.org/priceCurrency) property (with standard formats: [ISO 4217 currency format](http://en.wikipedia.org/wiki/ISO_4217), e.g. "USD"; [Ticker symbol](https://en.wikipedia.org/wiki/List_of_cryptocurrencies) for cryptocurrencies, e.g. "BTC"; well known names for [Local Exchange Trading Systems](https://en.wikipedia.org/wiki/Local_exchange_trading_system) (LETS) and other currency types, e.g. "Ithaca HOUR") instead of including [ambiguous symbols](http://en.wikipedia.org/wiki/Dollar_sign#Currencies_that_use_the_dollar_or_peso_sign) such as '$' in the value.
- Use '.' (Unicode 'FULL STOP' (U+002E)) rather than ',' to indicate a decimal point. Avoid using these symbols as a readability separator.
- Note that both [RDFa](http://www.w3.org/TR/xhtml-rdfa-primer/#using-the-content-attribute) and Microdata syntax allow the use of a "content=" attribute for publishing simple machine-readable values alongside more human-friendly formatting.
- Use values from 0123456789 (Unicode 'DIGIT ZERO' (U+0030) to 'DIGIT NINE' (U+0039)) rather than superficially similar Unicode symbols.
The currency of the price, or a price component when attached to [PriceSpecification](https://schema.org/PriceSpecification) and its subtypes.
Use standard formats: [ISO 4217 currency format](http://en.wikipedia.org/wiki/ISO_4217), e.g. "USD"; [Ticker symbol](https://en.wikipedia.org/wiki/List_of_cryptocurrencies) for cryptocurrencies, e.g. "BTC"; well known names for [Local Exchange Trading Systems](https://en.wikipedia.org/wiki/Local_exchange_trading_system) (LETS) and other currency types, e.g. "Ithaca HOUR".
One or more detailed price specifications, indicating the unit price and delivery or payment charges.
The date after which the price is no longer available.
A review of the item.
Review of the item.
URL of a reference Web page that unambiguously indicates the item's identity. E.g. the URL of the item's Wikipedia page, Wikidata entry, or official website.
An entity which offers (sells / leases / lends / loans) the services / goods. A seller may also be a provider.
The serial number or any alphanumeric identifier of a particular product. When attached to an offer, it is a shortcut for the serial number of the product included in the offer.
The Stock Keeping Unit (SKU), i.e. a merchant-specific identifier for a product or service, or the product to which the offer refers.
A CreativeWork or Event about this Thing.
URL of the item.
The date when the item becomes valid.
The date after when the item is not valid. For example the end of an offer, salary period, or a period of opening hours.
The warranty promise(s) included in the offer.