In an effort to improve the answers it supplies to more complex searches, Google has acquired online database provider Metaweb.

The five-year-old San Francisco startup maintains Freebase, an open database of information that catalogs more than 12 million "things" (data points from film titles to college-tuition prices) and how they relate. Other websites (including yours) can give their users access to Freebase by using plug-ins that let users search third-party content such as the New York Times, Twitter, and Hulu. (Is Metaweb good for your website? Watch this video.)

The acquisition price was not disclosed.

In a blog  titled "Deeper Understanding with Metaweb," Google's director of product development Jack Menzel announced the sale, saying it would "improve search and make the web richer and more meaningful for everyone."

He explained: "Type [barack obama birthday] in the search box and see the answer right at the top of the page...But what about [colleges on the west coast with tuition under $30,000] or [actors over 40 who have won at least one oscar]? These are hard questions, and we've acquired Metaweb because we believe working together we'll be able to provide better answers."

The database will be kept free and open, and Google urged other companies to contribute to its development by supplying data. (Curiously, Google made the official acquisition announcement right smack in the middle of Apple's iPhone antenna press conference.)

Veteran artificial intelligence researcher Danny Hillis and his two co-founders Robert Cook and John Ginnandrea launched Metaweb in July 2005. (To read an Inc. article about one of Hillis's previous startups, click here.) In March 2006 the company received $15 million in funding from investors including Benchmark Capital, Millennium Technology Ventures, and the Omidyar Network, eBay founder Pierre Omidyar's mission-based investment group. Later, investors poured another $42 million into the company.

Metaweb is the latest in Google's recent buying spree, which includes mobile-advertising firm AdMob and social-search service Aardvark.