"It's something the industry has been waiting on a long time," said Paul Kelley, an advertisement buying specialist with the Carat Fusion agency in San Francisco.
Second largest
Yahoo's new system further aims to enable advertisers to instantly calculate the cost of acquiring new customers.
Starting on Monday, it will then get a full launch in the autumn.
The company's chairman and chief executive Terry Semel said last month that he remained "very excited about Yahoo's prospects".
According to recent figures, Yahoo has a 27% share of the search engine market, behind Google's leading 42%.
Microsoft's MSN has a 13% stake, with Ask on 6%.
