Six percent of American adults who are online say they’ve visited Reddit, which encourages its users to submit links to stories, photos and other Web postings and then vote them up or down, according to results from a survey out Wednesday.

The report by the Pew Center’s Internet and American Life project, Pew’s first study of Reddit as a stand-alone platform, found that the site is most popular among younger men, with more than 18 percent saying they’ve visited the site, compared with 5 percent of women the same age. The gender divide holds throughout all the age groups, though the number of people who say they visit the site drops off significantly in older age groups, the study said.

As the site, which was founded in 2005 by University of Virginia classmates Alexis Ohanian and Steve Huffman and sold to Conde Nast in 2006, has evolved, so have its uses. And it should be no surprise that Reddit’s foray into social networking would follow in the footsteps of its bigger competitors Facebook and Twitter to also become a forum for political action and for tapping into the flow of wider online discussion.

Politicians and activists have used it to drum up grass-roots support — last year the site welcomed President Barack Obama to participate in its regular (mostly) open question-and-answer sessions, which the community refers to as “Ask Me Anything.”

In the wake of the Boston Marathon bombing, Reddit users submitted their theories about the bombers after combing through images and footage of the marathon — a development that drew some criticism. When some news outlets reported the user theories as if they were genuine law enforcement tips, Reddit general manager Erik Martin publicly apologized for the role the site played in what he called “online witch hunts and dangerous speculation.”

According to Reddit, the site’s viewership has soared in the past year, doubling its page views since 2012. In a company blog post last month, Reddit said it had logged 71 million unique visitors in May and was on track to hit 5 billion monthly page views later this year. Last year, the site reported about 2 billion page views and 34 million unique views in a month.

The survey statistics from Pew put Reddit about on par with the blogging platform Tumblr, the research firm said. By way of comparison, Pew determined that, as of last year, 16 percent of American adults online use Twitter and 67 percent use Facebook.

“Sites like Reddit are part of a larger digital ecosystem that is changing the process of news and information discovery,” report coauthor Maeve Duggan said in a statement. “Like all social media, it allows more direct citizen engagement in shaping the information ecology and produces cultural touchstones outside the bounds of mainstream media.”

The Pew study included 2,252 American adults contacted on landlines and cellphones between April 17 and May 19. Interviews were conducted in English and Spanish.