Yahoo has started publicly testing the latest in its search engine technology - contextual search.

The new service will generate queries on the fly based on the content of the Web page a user is reading, the company says. It comes in response to Microsoft's new MSN service launched earlier this week.

Yahoo says its new technology will make it easier and faster for users to find information than if they go through the conventional process of keyword-based search queries.

"Most people aren't skilled in the art of choosing exactly which keywords to use when searching," said Jeremy Zawodny, a Yahoo Search executive. "The fundamental idea [behind the new technology] was to supplement search queries with context."

Users can try out the new service, called Y!Q, in several ways. It has been implemented in a test Yahoo News environment available at http://test.news.yahoo.com/. Or you can download a new Yahoo toolbar that triggers contextual searches on any Web page. Or, Web publishers can embed Y!Q tags into their Web pages.

In all cases, the Y!Q queries and subsequent results are based on an analysis of the Web content a user actively highlights or is passively viewing. "Y!Q uses the context to help bridge the gap between query and intent," Zawodny said.

In Yahoo News, for example, headlines are accompanied with "search related info" links, which trigger a Y!Q search. A small search results box then pops up. With the DemoBar, users highlight portions of the text of the Web page they're visiting and click on a button to trigger a Y!Q contextual query. You need Internet Explorer or Firefox to see it.