Google Merchant Center
Google Merchant Center is Google's free tool where a store submits its product feed. That feed powers Google's Shopping results and, increasingly, its AI shopping surfaces through the Universal Commerce Protocol.
How it works
You connect your store or upload a feed, and Merchant Center holds a structured copy of your catalog: titles, prices, availability, identifiers, and images. Google reads from it to show your products, including in Google AI Mode and AI Overviews.
A commerce example
If your Merchant Center feed is missing categories or GTINs, Google's AI surfaces still show your products, just with less to match against a shopper's specific request, so you lose filtered comparisons.
What this means for your store
Keep the feed complete and current. It is one of the main pipes into Google's AI answers, and the Universal Commerce Protocol carries whatever quality you put into it.