Google Inc. has launched an online-publishing service that is a potential competitor to Wikipedia. Google on Wednesday took the wrappings off its previously announced publishing-and-reference service called Knol, which allows users to write articles on specific topics and to make money from them. By trying to provide such content, the service is likely to compete with online encyclopedia Wikipedia, whose articles tend to rank highly in Google search results. In an interview, Cedric Dupont, a product manager for Knol, described the service as a way to improve Google's search results by making the "information in people's heads" searchable. While Knol entries won't be given any preferential treatment in Google's search algorithm, Knol entries that are highly ranked by users could surface higher in search results if they are established to have quality content, he said. Google's service differs from the user-generated Wikipedia online encyclopedia in a number of ways. In particular, rather than stick to one article on a topic, Knol will allow many articles -- making it as much a collection of individual blogs as an online encyclopedia.