How it differs from a GTIN and a SKU
- GTIN — globally unique, allocated through GS1, the same for every seller.
- MPN — assigned by the manufacturer, unique within its catalogue.
- SKU — assigned by a seller for its own stock; two retailers selling the
same item use different SKUs.
A model can use a SKU only on the page where it appears. An MPN and a GTIN travel between pages, which is what makes them useful for identity.
Example
A camera body sold by three retailers carries three SKUs, one MPN and one GTIN. If only the SKUs appear in the HTML, nothing tells a model the three listings are the same camera.