Google Instant promises live search results
Google has sped up its internet search engine by launching a product called Instant that displays results as soon as users type in queries.
The service predicts a user's query and modifies the displayed results as more letters are typed into the search box.
The company described it as "search at the speed of thought".
Previously Google's suggested search terms and did not reveal results until the "enter" key was hit or the "search" button was clicked.
Google Instant goes live in the next week and on mobile devices by autumn.
The service will initially be rolled out in the US, UK, Spain, Germany, France and Russia.
Challenge to Microsoft?
In a demo event held at San Francisco's Museum of Modern Art, Marissa Mayer, Google's vice-president of search products and user experience, typed in "sfm" into the search box to demonstrate the new service.
As she typed, results appeared instantly for "SF MOMA" - the first predicted search result.
In another demo, when the letter "w" was entered, a list of links offering the "weather" appeared along with images showing the temperature.
"We've actually predicting what query you are likely to do and we're giving you results for that," said Ms Mayer.
Google estimates that the typical user spends nine seconds entering a query and 15 seconds looking for answers.
The company says Google Instant could shave between two and five seconds off a typical web search.
"Google is betting all they have that speed is everything," Harry McCracken of technology blog Technologizer.com told the BBC.
"Saving one or two seconds isn't that big of a deal. One of my instant thoughts is that I am going to see results I don't want because until I type enough that it knows what I want, it is going to show me links I am not interested in."
Technology commentator Robert Scoble said that the new feature would present a real challenge to Microsoft search engine Bing, which has been slowly chipping away at Google's lead in the search market.
"Playing with it, it dramatically changes the way I do searches. I think it is a pretty major leap forward but this means that Bing becomes far less interesting and they now have to step up," said Mr Scoble.
Microsoft currently commands around 11% of the US search market compared to Google's 66%, according to research firm Comscore.
Bing has gradually increased its market share since launch, although its growth has recently slowed.
By Maggie Shiels
Technology reporter, BBC News, Silicon Valley