Definition: CPA is an Internet marketing model where advertisers pay for each time a user takes a specific action. Usually this means every time someone clicks on an ad and buys something.
Google has experimented with CPA advertising in their AdSense program.
Microsoft launched a CPA program for their search engine in May of 2008. Live Search cashback offers users cash rebates on any purchases they make. As of this writing, Google has not announced any plans to offer a similar program.
