About advertising with Comparison Shopping Services

Yes, only CSSs can place Shopping ads. You can use Google Shopping or any other CSS of your choice. You can also participate via several CSSs at the same time.

No. CSSs (including Google Shopping) pay Google for clicks on the ads that they place. CSSs can choose how to invoice their merchants. For example, Google Shopping generally charges its merchants based on a CPC model.

Note that clicks on the 'By CSS' link at the bottom of the ads (which lead to the website of the CSS) are currently free for CSSs.

We do our best not to show multiple instances of the same offer (that's the same product offered by the same merchant). If we identify that several CSSs have uploaded the same product from the same merchant, we will only show it once in the ad unit. In the rare cases when we cannot detect that two offers are the same, they may both show up in the same Shopping unit. The CPCs paid by the winning CSSs do not increase in such a scenario because a merchant is never second-priced against itself (refer to the next question).

Different products from the same merchant can appear via several CSSs in the same unit. For example, if a user searches for running shoes, one model of running shoe that you sell may appear in an ad from CSS A while another model appears in an ad from CSS B. The CPCs paid by the winning CSSs also do not increase in such a scenario because a merchant is never second-priced against itself (refer to the next question).

A merchant will never be second-priced against itself in the auction for any offer, irrespective of the number, or identity, of the CSSs used by the merchant. Therefore, if two CSSs place bids on behalf of the same merchant, the winning offer and the price paid by the winning CSS will be the same as if those bids had been placed by the same CSS.

The fact that several CSSs place ads on your behalf won't mean that your offers are being repeated or that Google will charge more for a click on any of them.

Example: CSS A bids 30 pence per click to place your offer. For simplicity, we'll assume that all ads have the same quality and relevance.

Scenario 1: The next highest CSS bid is 20 pence on behalf of a different merchant. Your offer will win the auction at a cost of 20 pence – only as much as necessary to maintain the position.

Scenario 2: Now assume that another CSS starts advertising on your behalf and bids 25 pence. You still win the auction with the 30 pence bid that CSS A made on your behalf, but the next closest competitor now bids 25 pence. Since this competitor is a CSS who's also bidding on your behalf, we do not use that second bid to determine the price that CSS A pays. Instead, we find the next highest bid that's been placed for a different merchant, which is still 20 pence. The CPC paid for the winning bid does not change and remains at 20 pence.

Scenario 3: Now assume, instead, that the bid placed on your behalf by CSS B is higher than the bid placed by CSS A on your behalf. In this case, CSS B will win the auction. The next highest bid is the 30 pence bid that CSS A placed, also on your behalf. Since both bids are for the same merchant, we do not use CSS A's bid to determine the price of the click that CSS B pays. Instead, we use the next highest bid for a different merchant, which is still 20 pence. The CPC paid by CSS B for your product will be 20 pence.

CSSs typically report the number of clicks sent to a merchant and the cost charged per click. Depending on their pricing scheme, they may also report additional information or share detailed bidding data. Google Shopping also reports the number of clicks sent to a merchant and the cost charged per click, together with other metrics. The European Commission requires Google Shopping to be independently profitable in EEA countries where Shopping ads are available. Google Shopping currently ensures profitability by deducting a fixed percentage margin from each merchant bid before entering it into the auction. The margin is included in the CPC paid by the merchant and is charged only when a user clicks on one of the merchant's ads. In general, we recommend that merchants compare the costs and returns of different marketing channels to assess which ones work best for them.

Shopping ads placed by CSSs (including Google Shopping) are shown on Google general search results pages. To avoid user confusion, they also have to be shown on the website of the CSS that submitted them (in the case of Google Shopping, the site at google.com/shopping).

Sign in to your Merchant Center account. Go to Your business, then go to the Comparison Shopping Services tab. Click to expand the CSS section. You will find a list of all CSS that have uploaded products from your website. You can also find contact information for each of them. If you don't have a Merchant Center account for the domain in question, you can create one for free.

What works best for you depends on your business, your goals and the services offered by CSSs. You can advertise with several CSSs at the same time to determine the best combination for you. All CSSs, including Google Shopping, have the same opportunities to place ads on your behalf on Google general search results pages. No ad space is reserved for any particular CSS.

Different CSSs may provide different value-added services. However, we understand that you may want to control how your ads are appearing. We recommend that you reach out to the relevant CSS to discuss any concerns that you might have (your Merchant Center dashboard provides the customer service website, phone number and email address for each CSS.) All CSSs can adjust the volume of traffic that they are sending you using bids and budgets, and they can also pause or activate campaigns. Some CSSs allow their merchants to control campaigns directly through an interface that they provide. You can also use the dashboard in Merchant Center to opt in and out of a particular CSS channel.