product identifiers
Also called: unique product identifiers, upi
Product identifiers are standardized identifiers, mainly GTIN, MPN, and brand, that pin down exactly which product a listing refers to. Google uses them to match your listing to the same item sold elsewhere, so accurate identifiers help your products qualify for Shopping and merchant listing rich results.
The three identifiers Google leans on are GTIN (Global Trade Item Number, the code behind a UPC, EAN, or ISBN barcode), MPN (Manufacturer Part Number), and brand. Together they tell search engines “this is the exact same product being sold over there,” which lets Google group offers, build Shopping knowledge panels, and match your page to buyer queries.
Where they live and why accuracy matters
In a Merchant Center feed they are the gtin, mpn, and brand attributes. On your product pages they belong in Product structured data as the gtin, mpn, and brand.name properties. Google’s guidance is blunt: “Products with an assigned GTIN, but submitted without one, may have limited visibility.” The same warning covers brand and MPN.
Rules that trip stores up:
- Do not invent or guess identifiers, and never paste your internal SKU into the
gtinfield. Incorrect values can get products disapproved. - If an item genuinely has no GTIN (custom-made, vintage, or store brand), leave it out and set
identifier_existstonoso Google knows the omission is intentional. - Use the most specific GTIN that applies, in numeric form.
Getting these right is quiet, unglamorous plumbing, but it is often the difference between a product page that earns rich results and one Google treats as unmatched inventory.
How it affects your traffic
Missing or wrong identifiers are one of the most common reasons product pages fail to earn merchant listing rich results or get disapproved in Shopping, quietly capping the traffic a well-built catalog should pull. Auditing GTIN, MPN, and brand coverage across a feed and the on-page Product schema is standard work in an e-commerce engagement, and fixing it can unlock visibility you already qualified for without writing a single new word. For large catalogs, this technical cleanup is exactly what our E-commerce SEO service handles.
Get E-commerce SEO that moves the needle
We turn terms like this into ranked pages and qualified pipeline. Start with a free Initial SEO Strategy.