A product feed is a structured file, usually XML or CSV, that lists every product you sell with its id, title, description, price, availability, image and link, in the format a sales channel asks for. Google Shopping, Meta, Microsoft, ChatGPT and price comparators all read one to show your products.
Every product you've ever seen in a Google Shopping result, tagged in an Instagram post, or listed on a price comparator got there the same way: through a product feed. If you're about to advertise your catalog anywhere beyond your own site, this file is the first thing you'll be asked for.
The one-sentence version
A product feed is a structured file — usually XML or CSV — that lists your products with the exact fields each channel expects: title, description, price, currency, stock status, image, barcode (GTIN), brand, and a link to the product page. Channels don't browse your website; they read this file.
Who reads it
Google Merchant Center feeds Google Shopping ads, free listings and Performance Max. Meta Commerce Manager powers Facebook and Instagram catalog ads and product tags. Microsoft Merchant Center does the same for Bing. Price comparators like Heureka, Compari and Árukereső list your offers next to competitors'. ChatGPT reads product feeds in OpenAI's own format: in ads, through OpenAI Ads Manager, and in shopping results, from merchants OpenAI has approved. Same catalog, five different specs.
Why the same file keeps breaking
Each channel validates the feed against its own rules, and rejects what doesn't comply — silently dropping the product from ads. The classics: a missing or invalid GTIN, an image that's too small or has a watermark, a feed price that no longer matches the page price after a sale started, and stock status that went stale because the file was generated yesterday.
Static export vs. managed feed
Most platforms can dump a one-off export, and for a first test that's fine. The problems start with time: prices change, products sell out, and the exported file doesn't know. A managed feed re-reads your store continuously, rebuilds the file fresh every time a channel fetches it, and validates the fields before the channel sees them — so a price change in your store this morning is what Google reads this afternoon.
What to do next
If your platform already generates a feed URL, check it before pasting it anywhere: paste it into a feed checker and see what Google would reject. If you're starting from zero, connect your store to a feed tool and let it generate the per-channel files for you — that's exactly what FeedRobin does, for every channel above, from one catalog.
Sources
The field lists above come from each channel's own documentation: Google's product data specification, Meta's catalogue product data specifications, OpenAI's product feed specification and Heureka's offer feed XML documentation. Where ChatGPT shows products from a feed: OpenAI Help Center, Create Campaigns from Product Feeds, and OpenAI Developers, Agentic Commerce: Get Started.