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The new service, called Live Search Cashback, will refund a percentage of the cost of a selection of products from participating retailers.

Searches will return standard results alongside paid results from these retailers, which will be highlighted by a small yellow icon.

The cash rebates will be funded

Unlike Google's technology, Microsoft's new system charges advertisers only when a transaction is completed.

Google's cost-per-click model does not guarantee that a browser will go on to actually buy a product or service they see advertised on search results, and instead charges for all clicks.

The technology is based in part on software from Jellyfish, an advertising firm that Microsoft acquired in 2007. The company operates a website where customers can compare the price of products at several retailers. Those retailers pay Jellyfish for featuring products, and a portion of that fee is given to the customer as a rebate.

The Jellyfish site was down at the time of publication, however, with a notice on the front page claiming that the downtime is needed to "perform necessary service upgrades and enhancements".