Microsoft Corp. (MSFT) finally debuted its own Web search technology on Thursday, hoping to challenge Google Inc.'s (GOOG) long dominance of the field with results tailored to a user's location and answers from its Encarta encyclopedia.

Google signaled that it is ready for a fight, announcing Wednesday that it would nearly double the amount of Web pages available to search through its site.

The Microsoft search engine, offered in 11 languages, will initially be available on a special "test" site. Gradually, some users visiting Microsoft's MSN site may find that the existing search bar uses the new search engine, said Adam Sohn, a director with the company's online division. But a full rollout, perhaps with new features, isn't expected until early next year.

Redmond-based Microsoft has long offered a search engine on its MSN Web site, but the technology behind was powered by subsidiaries of Yahoo Inc. (YHOO)

Earlier this year, company executives conceded that they had erred by not developing their own search technology and said they had devoted $100 million in an aggressive catch-up effort. The company also pledged to clearly separate paid search results from those based purely on the relevancy. That's something its previous search engine hadn't done but that the new technology will do.

Microsoft also plans to offer by year's end a test version of its hotly anticipated technology for quickly locating e-mail, Web pages and other files on desktop computers. Google launched a similar product last month.

Hoping to steal some of Microsoft's thunder, Google nearly doubled the size of its search engine index to more than 8 billion Web pages Wednesday evening. A Google spokesman downplayed the Microsoft connection, saying the Mountain View-based company had been working on the expansion for months. Google last expanded its Web index to 4.3 billion pages in February when another rival, Yahoo Inc., unveiled a search engine powered by its own in-house technology.

Microsoft says its site will sort through more than 5 billion Web pages.

Analysts say that just because Microsoft is a late entrant doesn't mean it won't pose a formidable threat to Google, Yahoo and others.

Microsoft's search offering has many features likely to appeal to users who don't care about particular brands, according to Charlene Li of Forrester Research.

A feature called "Search Near Me" guesses where users are located based on their Internet connections and seeks to provide results nearby. Another feature promises to answer plain-language questions such as "What is the capital of Germany?" by culling through Encarta (search).

Google also offers a localized search function, with users telling the search engine where they are. And it has a "Google Answers" site, where researchers provide data for a minimum fee of $2.50. Microsoft's version is free but not as tailored.

Li also said Microsoft has another advantage in that many users already visit its MSN Web site and are familiar with other products such as its dominant Windows operating system or Hotmail e-mail.

In trading Wednesday on the Nasdaq Stock Market (search), Microsoft shares closed 4 cents at $29.73, while Google shares lost 84 cents to $167.86 and Yahoo shares finished off 37 cents at $36.66.