Google will make a significant push toward integrating results from a variety of its search engines in an attempt to deliver as relevant and comprehensive a result set as possible to search queries.

Although Google and its competitors have been moving in this direction for years, Google's announcement is its clearest and most concrete statement of direction yet regarding its efforts in this area. The announcement was made by Marissa Mayer, Google's vice president of search products and user experience, at an event in the company's headquarters.

Internet sites like Google and Yahoo offer, in addition to their general web search engines, a set of specialty engines that deliver only news articles, photos, local business listings, blog postings, maps or video clips.

These companies have long recognised that it is inconvenient for users to have to use different engines for the same query, particularly because it is often relevant to see, for instance, webpages, images and maps to satisfy searches.

Moreover, studies have shown that many people don't even realise that these companies have specialty search engines beyond their main search sites.

"It's an acknowledgement by Google that users aren't going to these vertical search sites where Google has lots of valuable links to crawled content," said industry analyst Greg Sterling of Sterling Market Intelligence. "This is a way to expose users to these links without having them go to the vertical engines."

Google and its competitors know that in order to improve the average user's search experience, they need to collate results from their different engines. As the operator of the world's most popular search engine, Google has more riding on this than its competitors. Almost all of Google's revenue is generated from ads it runs along with its search engine results.

To that end, Google announced it is moving towards what it calls a "universal search model", while acknowledging it is still far from where it wants to be in this area, which is to deliver a single set of results culled from all its engines.

Results of this effort will be often subtle and gradual, the company warned. As part of the effort, Google is implementing a new technical infrastructure able to handle the intensive computational tasks involved in providing integrated results. An upgrade to the results ranking mechanism is also being rolled out.

The integrated results will be applied for now to searches conducted on the main search engine only, a Google spokeswoman said.

Google's competitors have also begun integrating results from their engines in various ways and with different approaches, but with the same goal in mind: improve the search experience for users.

The universal search improvements look incremental, considering Google has been including results from some of its other engines in results for some time. However, Sterling added that it will be interesting to see how users react to a more deliberate effort to integrate different engines' search results.

"It will also be interesting to see how users react to having to scan over more result options in the first page of results," he said. "People usually give a quick scan to the first five results and rarely scroll down the page or click on over to the second page of results."

Google also updated its homepage design and tweaked navigation features to accommodate the collated set of results.

Google has also released a service called Google Experimental available on its Labs site.

The announcements were made at the three-hour event, called Searchology, which also featured as speakers Udi Manber, vice president of engineering, and Craig Silverstein, technology director. It came amid much publicity in recent months over Google's nascent efforts in the market for business-hosted applications.

"The entire event is a reminder that Google continues to invest aggressively and heavily in search," Sterling said.