MPN
An MPN (Manufacturer Part Number) is the code a manufacturer assigns to a specific product, used to identify it when a universal barcode like a GTIN is not available.
The MPN is the manufacturer's own internal reference for a part or product. Unlike a GTIN, it is unique only within that manufacturer's lineup, so an MPN on its own does not pin down a product globally. Paired with the brand, though, it becomes a reliable identifier.
It matters most for products that lack a GTIN, like components, replacement parts, or items from manufacturers who never assigned a barcode. In those cases channels accept the brand plus MPN combination as a valid identifier so the product can still compete in shopping placements.
In the feed it lives in the mpn attribute and is almost always submitted alongside brand. A common error is confusing the MPN with your own retailer SKU; the MPN comes from the manufacturer, not from your store's internal numbering.
MartechFlow lets you map the right source column to mpn, keep it paired with brand, and validate that products without a GTIN still carry an acceptable identifier combination before the feed goes out.