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NEW YORK (CNNMoney) - Facebook has built a world where nothing is off limits.

Addressing employees at Facebook's headquarters in Menlo Park, Calif., CEO Mark Zuckerberg admitted that the company's "community standards are not perfect" and admitted he's made mistakes that have caused "communities to be hurt and people to be angry."

"We've built a very strong community with hundreds of millions of people using Facebook every day," Zuckerberg said, according to a copy of his memo reviewed by CNNMoney. "We now need to work really hard to show all of these communities and individuals that we care about them and want to work with them."

Zuckerberg announced new rules last November to strengthen policies around how the company monitors and polices its platform for hate speech, extremist groups and harassment. Facebook began flagging content in the fall to create an automatic version of the human review process.

Facebook updated its guidelines to ban an entire category of content. The company removed 464 categories of material from its "community standards," such as material about drug use and hate speech. The company said it expected "the majority of these categories" to be taken down by the end of 2018.

At least two dozen groups are still missing from the lists -- and experts say more could follow.

"The problem now is that Facebook has thrown away the old playbook on how to stop abuse on the Internet," said Fred Jacobs, co-founder of the Media Analytics Institute, which studies online media. "Because of those efforts, Facebook needs to be careful that everyone else not fall victim to the new system."

In the memo, Zuckerberg encouraged employees to "correct mistakes, get things right in the future, learn from the mistakes and get back to serving our community as best we can."

Facebook also faces the challenge of managing content from users in countries that have different laws and expectations for content. In 2017, for example, Facebook banned hate speech and violent groups from Iran after the country's judiciary agency reported that over 400 people -- including several activists and journalists -- were arrested for "anti-revolutionary content."

Zuckerberg criticized journalists' reporting on Iran, pointing to a 2015 BuzzFeed News article titled "How Facebook's blocking of Iran's Islamic State supporters confused everyone." He described the report as "journalistic misrepresentation."

This week, Reuters published a story about a Facebook contractor and author giving purported advance notice that a government would ban an Iranian human rights activist from the social network.

"Media companies and journalists tell stories about the world we live in. We tell stories that we see or believe are important in the world. This happens in every newsroom everywhere," he wrote. "The essence of the relationship is that Facebook's stories change the world. When we tell the news, we don't censor. We amplify voices, give readers information and improve democracy."

Zuckerberg said the company plans to hire 20,000 people over the next year, both to respond to reports of suspicious activity on the platform and monitor content.

His plan is "another big stretch" for Facebook, he said.

"We are already the biggest global media company, with 11 times more employees than the next biggest media company on the planet," he said. "Now, we're also going to build the best global safety team."

Updated Wednesday, February 6: Reached for comment, a Facebook spokesperson said Zuckerberg's memo was aimed at "communicating news about our community standards and product updates to team members." The spokesperson reiterated that these new policies are "aimed at improving the safety and security of our community for every one of our users around the world."

CNNTech’s Josh Taylor contributed to this report.


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