The mechanism is worth understanding because it explains most of the problems people have. You submit a feed containing a row per product with required attributes: identifier, title, description, price, availability, image, and category. The system validates it, and anything failing validation simply does not appear. Most businesses whose products are not showing have a feed error rather than a bidding problem, and the diagnostic is in the merchant interface rather than in the advertising account.
There is a free option that many businesses do not realise exists. Unpaid product listings appear in some surfaces without any advertising spend, which means completing the merchant setup and submitting a valid feed has value even if you never run a campaign. That is a reason to do the setup work early regardless of budget.
The feed quality determines performance more than the bidding does. Titles carry disproportionate weight, and a title structured as brand, product, and key attribute will outperform a creative name. Images must meet requirements and a clean product image on a plain background consistently outperforms a lifestyle photograph. Missing identifiers on products that should have them suppress visibility entirely.
If you use a mainstream store platform, an application will generate and maintain the feed automatically, which is the correct approach. Building a feed by hand is possible and creates a maintenance burden you will not sustain, since it must reflect price and stock changes continuously.
Check the merchant interface weekly for the first month, because product disapprovals happen quietly and the items simply stop appearing. Common causes are price mismatches between the feed and the landing page, missing shipping or tax configuration, and image requirements. None are difficult to fix and none announce themselves, which is why a business can conclude the channel does not work while half its catalogue is silently excluded.
Set up the free listings before spending anything, since the merchant setup and a valid feed produce visibility in some surfaces at no cost. Businesses frequently treat the whole thing as an advertising decision and defer the setup until they have a budget, which delays the free portion for no reason. Get the account verified and the feed accepted, then decide separately whether to advertise.