Facebook is buying a set of online advertising tools called Atlas from Microsoft in its latest attempt to build a more effective marketing system around its Internet social network.

In making the deal announced Thursday, Facebook is betting the acquired technology will bear more fruit under new ownership than it did during the past five-and-half years under Microsoft's control.

Atlas is part of an online advertising service called aQuantive that Microsoft Corp. bought for $6.3 billion in 2007. AQuantive didn't bring in as much online ad revenue as Microsoft envisioned, prompting the software maker to absorb a $6.2 billion charge last year that resulted in its first quarterly loss in its 26-year history as a public company.

Given the magnitude of that writedown, Facebook probably didn't have to pay much. Facebook didn't disclose the purchase price, another sign that the amount isn't substantial enough to significantly affect the company's finances.

Atlas provides monitoring tools that help advertisers assess how their online marketing tools are faring and make adjustments needed to connect people more likely to buy their products and services.

Facebook Inc. already analyzes the interests that people share on its social network to target ads at certain audiences.