Yahoo rolled out part of a new advertising platform on Wednesday that's intended to streamline how digital ads are bought and placed across the Web.

The platform, APT, has been under development for at least two years. APT has been one of Yahoo's big projects undertaken to improve its mediocre financial performance and grab a larger slice of rising Internet advertising revenue.

Yahoo hastily previewed APT, then known as AMP, in April, as the company was under intense pressure caused by Microsoft's acquisition attempt.

The APT Web site is short on details, but the company outlines its features.

APT aims to link Web site owners, advertisers and the agencies between them who sell ads. It's an automated platform that gives advertisers a range of tools to control where ads should appear, what kind of Web surfers the ads should be shown to, and how much they are willing to pay.

Yahoo's strength has been in display advertising area, while Google has built its robust business on text-based ads that can be incorporated into Web sites with similar content. Google, however, is also diversifying its platform for display ads and Microsoft also remains a key player.

Two newspapers, the San Francisco Chronicle and the San Jose Mercury News, will use APT, Yahoo said. The publications are part of a Newspaper Consortium established in 2006, in which the papers share ad revenue with Yahoo in exchange for technical assistance.

Yahoo said more of the consortium's 784 newspapers will adopt APT through next year.

APT can serve ads, meaning it places an ad in the right spot at the right time on a publisher's site. It also is its own ad network, which links advertisers and publishers, and an ad exchange, where ads can be bought and sold. Ad exchanges help publishers find ads to show when they have unsold spaces.

Yahoo says APT can deliver ads based on where a person is browsing the Internet from and based on their online behavior. Those targeting capabilities are increasingly being demanded by advertisers, who don't want to spend money showing ads to people who are likely not interested in their product.

APT also has other tools for publishers, such as managing the schedule of when ads will be shown and tools that help ensure all available ad space is sold.