The Microsoft-Yahoo pact is a measured step that represents a pragmatic division of duties between the two companies, instead of the blockbuster deal Microsoft initiated last year, when it bid $47.5 billion to buy Yahoo. That hostile offer was ultimately withdrawn by Microsoft, and its collapse led to a management change at Yahoo and the replacement of its co-founder Jerry Yang with an outsider, Carol Bartz, in the chief executive role.Under the pact, Microsoft will provide the underlying search technology on Yahoo’s popular Web sites.

The deal will give a lift to Microsoft’s search engine, which it recently overhauled and renamed Bing.Bing, which tries to put search results in better context than rivals, has won praise and favorable reviews, after Microsoft spent years falling further and further behind Google in search.With the addition of Yahoo’s users, Microsoft will be able to run more searches through the Bing technology infrastructure.

It expects to deliver better answers to search queries over time as well, by learning from more peoples’ queries.For Yahoo, the move furthers the strategy under Ms. Bartz to focus the company on its strengths as a producer of Web media sites, from finance to sports, as a marketer and as a leader in online display advertising.