Wikipedia has continually altered its rules and guidelines over the years to prevent these sorts of problems, including: emphasizing neutral points of view, pushing for links to original sources like studies or news articles, providing tools to flag articles that lack proper documentation and granting the most reliable editors additional rights to review material before it's published.

Collectively, the tweaks have helped boost usage by assuaging early concerns that information anyone could submit or change - regardless of expertise or agenda - would inevitably be flawed, said Lee Rainie, director of the Pew Research Center's Internet & American Life Project.

"It's not like they wholesale trust everything they encounter, but it's served their needs often enough and reliably enough so that they don't recoil from it by default," he said.

Indeed, as of May, 42 percent of all U.S. adults (or 53 percent of adult Internet users) used Wikipedia to look up information, an increase from 25 percent in February 2007, according to a Pew survey. That makes it more popular than instant messaging. For Internet users with at least a college degree, the number jumps to 69 percent.

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