verture Services, the leading seller of advertising that accompanies and looks like the results of Internet searches, said yesterday that it had agreed to buy AltaVista, one of the first Internet search engines, for $140 million.

AltaVista is owned by CMGI, the one-time highflying Internet holding company, which bought it from Compaq Computer in 1999 for $2.3 billion. Compaq had acquired AltaVista as part of its purchase of the Digital Equipment Corporation, which started AltaVista as a demonstration project for its technology.

The move positions Overture to battle on all fronts with Google, which has become the leading search engine in terms of audience. Google leapfrogged its rivals with technology that can comb through billions of Web pages quickly to find those that are most relevant to whatever phrase is entered by the user.

Over the last year, Google has also become a potent threat to Overture in selling search-related advertising, and it won away Overture's biggest client, America Online, offering a combination of traditional search results and advertising related to users' searches.

Yahoo, which had been the No. 1 search site before Google's rise, had used Google for its search engine and Overture for search-related advertising. But in December, it purchased Inktomi, another provider of Web search technology, for $235 million.

The advertising sold by both Overture and Google is typically placed above or to the side of the results of the Web search, in a similar type face, identified with a phrase like "sponsored listings." Overture charges a fee to the advertiser when users click on a link to their site. Advertisers that offer to pay the most per click are listed first.

The acquisition represents a bit of an about-face for Overture. When it was founded in 1998 as Goto.com, it encouraged users to conduct their Web searches at its site, which had only paid listings. In 2001, it changed its name and stopped marketing its own search site, so it would not be seen as competing with its customers (as it says Google does).

Ted Meisel, Overture's chief executive, said the company would continue to operate the AltaVista.com site and would use it to test new technology. But he said its main goal for the acquisition is to gain control of its own search technology and AltaVista's technical staff of 100 people. He declined to say how many of AltaVista's 250 employees will be offered jobs.

While AltaVista has lagged Google and others in search technology, Mr. Meisel said he did not see that as an irreparable handicap.

"We think it is still really early in the game," he said. "And search is a media property, and there will be more than one platform."

Mr. Meisel declined to discuss the revenue, profits or audience size of AltaVista or to disclose Overture's specific plans. He said these would be revealed to investors later. The company did say that it expected the deal, which involves cash and stock, to reduce earnings per share this year and increase them next year.

One way that AltaVista will make money for Overture is through what is called paid inclusion — charging Web sites to have more of their pages included in the search results. Typically search engines, like AltaVista, will index the home page and a handful of other pages on any Web site. If the Web site owner wants more pages searched — each product in a catalog, for example — companies like Inktomi and AltaVista charge for additional referrals that result. (Google, so far, does not charge for inclusion in its index.) Mr. Meisel said that the paid inclusion market was far smaller than its existing search advertising business.

Overture announced its acquisition at the end of the regular trading session. In after-hours trading, its shares fell to $20.80, after closing at $22.79. Shares of CMGI rose to $1.05 in after-hours trading.