Racing to Fill Gaps Left by Google

The race to build a successor to Web search is heating up as a number of young companies seek to fill gaps they see with Google.

One of the hopefuls, Quora, made its public launch Monday after months of private testing. The company, co-founded by two early Facebook Inc. engineers, wants to collect and organize information people have in their heads but that may not be available online, such as background on the inner workings of a company and advice on how to get a reservation at an exclusive restaurant.

Similar services such as Mahalo and Aardvark, recently acquired by Google, have developed improved ways to show the right questions to the people who can best answer them. Some are also encouraging users to use their real identities. Their efforts illustrate the continual evolution of Web search, which is constantly adapting to new content. Once capable of spitting out links to websites, search engines now directly yield results like photos and videos and maps. Yet even search leaders like Google acknowledge Web search falls far short of its goal of delivering any answer to any question. Google's main gateway is still a search box, which is most useful when people have a fairly specific search term in mind.