WSJ.com: “More than 100 interviews and the Journal’s own testing of Google’s search results reveal:

• Google made algorithmic changes to its search results that favor big businesses over smaller ones, and in at least one case made changes on behalf of a major advertiser, eBay Inc., contrary to its public position that it never takes that type of action. The company also boosts some major websites, such as Amazon.com Inc. and Facebook Inc., according to people familiar with the matter.
• Google engineers regularly make behind-the-scenes adjustments to other information the company is increasingly layering on top of its basic search results. These features include auto-complete suggestions, boxes called “knowledge panels” and “featured snippets,” and news results, which aren’t subject to the same company policies limiting what engineers can remove or change.
• Despite publicly denying doing so, Google keeps blacklists to remove certain sites or prevent others from surfacing in certain types of results. These moves are separate from those that block sites as required by U.S. or foreign law, such as those featuring child abuse or with copyright infringement, and from changes designed to demote spam sites, which attempt to game the system to appear higher in results.
• In auto-complete, the feature that predicts search terms as the user types a query, Google’s engineers have created algorithms and blacklists to weed out more-incendiary suggestions for controversial subjects, such as abortion or immigration, in effect filtering out inflammatory results on high-profile topics.
• Google employees and executives, including co-founders Larry Page and Sergey Brin, have disagreed on how much to intervene on search results and to what extent. Employees can push for revisions in specific search results, including on topics such as vaccinations and autism…”