What is Reddit?

That's the $50 million question the company and the 164 million people who visit the site each month are grappling with.

The company's co-founder and new CEO, Steve Huffman, on Thursday laid out a set of new policies that will restrict what users can post on the site.

"As Reddit has grown, we've seen additional examples of how unfettered free speech can make Reddit a less enjoyable place to visit, and can even cause people harm outside of Reddit," he wrote under his username "spez" at the beginning of a town hall forum on the site called an "Ask Me Anything," or AMA.

Among the posts that are no longer allowed:illegal activity; publication of people's private information; anything that incites violence, harassment, bullying, abuse; and anything sexually suggestive of minors.

"We've spent the last few days here discussing and agree that an approach like this allows us as a company to repudiate content we don't want to associate with the business, but gives individuals freedom to consume it if they choose," he added. "This is what we will try, and if the hateful users continue to spill out into mainstream reddit, we will try more aggressive approaches."

For years since its founding in 2005, the site has been a free-wheeling, nearly anything-goes collection of Internet forums run primarily by volunteers and users, who call themselves Redditors. It's been the home of people discussing their struggles with cancer, swapping theories about "Star Wars," and debating politics. It's become one of the most popular websites in the world, leading the company to describe itself as "the front page of the Internet."

But it's become home to some of the worst aspects of Web culture as well. In the past year, Reddit has become a haven of racist and hateful communities. Redditors were also at the center of a nude-celebrity photo-hacking scandal. And the site has served as a staging ground for attacks against feminist critics of video games.

Reddit has seen change in the past year. Three people have occupied its CEO job since November alone. The company has also seen the return of its other co-founder, Alexis Ohanian, as executive chairman, and a $50 million investment from some of Silicon Valley's top money men. But with that money has come an expectation that Reddit will be more than a loose collection of Internet forums where anything goes. It's expected to become a place that will capitalize on its popularity.

"The trolls are winning," Ellen Pao, Reddit's former CEO who stepped down last week, wrote Thursday in an opinion piece in the Washington Post. "We were naive in our initial expectations for the Internet, an early Internet pioneer told me recently. We focused on the huge opportunity for positive interaction and information sharing. We did not understand how people could use it to harm others."

Now, industry insiders say Reddit must balance what it wants to be with what its users expect.

"There's a huge schism that has appeared between the business and users -- the culture," said David Weinberger, a senior researcher at Harvard's Berkman Center for Internet and Society. "This is important because the product is the community, unlike Amazon or something. If you alienate your users, there's no product left; the thing of value is the community they've built."

Reddit's executives seem to understand that particular challenge. "No company is perfect at addressing these hard issues," Huffman wrote. "Freedom of expression is important to us, but it's more important to us that we at Reddit be true to our mission."

Reddit is part owned by Advance Publications, the parent company of Conde Nast, which publishes magazines including GQ and Vanity Fair. It also raised $50 million in funding from prominent venture capital firms Andreessen Horowitz and Sequoia Capital, high-profile investors Ron Conway and Peter Thiel, and entertainers such as Jared Leto and Snoop Dogg.

The debate rages on

Users participating in the forum were quick to push back on Huffman, and the new rules he appeared to be imposing on the company. There were more than 8,000 comments posted within the first hour of Huffman's AMA.

Some seized on the perceived inconsistency between the company's mission as a home of thoughtful debate, and the home of free speech that users have come to expect. Since taking over Tuesday, Huffman and Ohanian have begun reminding users of this difference, presumably in preparation for the new rules they planned to impose.

As an example, Huffman pointed to a community called RapingWomen, as one that would definitely be banned from the site. "They are encouraging people to rape," he wrote.

One member, Seven-Three, was dismissive: "So speech that you like is fine, speech that you don't like isn't. Got it."

Another user, Warlizard, asked how much of this push is motivated by Reddit's need to make money. "Zero," Huffman wrote.

To Susan McGregor, assistant director at Columbia's Tow Center for Digital Journalism, these new changes represent Reddit's shift toward an editorial voice, even if it clashes with what some of its users prefer. "It's becoming more and more clear that these changes are coming from the long-term management," she said. "And it's a sign of the maturation of the platform in general."