Facebook will allow users to turn off Beacon, a highly criticized ad platform that notifies users' friends of their purchases on other sites.

Facebook founder Mark Zuckerberg apologized in a blog post Wednesday for mistakes in building the feature, as well as mistakes in handling complaints about it. He explained that users can now opt out of the system

"We simply did a bad job with this release, and I apologize for it," he wrote. "I'm not proud of the way we've handled this situation and I know we can do better."

Zuckerberg said that when Facebook considered Beacon it hoped to let people share information across sites with their friends. He said it had to be clear and easy to control, while also being "lightweight so it wouldn't get in people's way as they browsed the Web."

He continued, "We were excited about Beacon because we believe a lot of information people want to share isn't on Facebook, and if we found the right balance, Beacon would give people an easy and controlled way to share more of that information with their friends. But we missed the right balance. At first we tried to make it very lightweight so people wouldn't have to touch it for it to work."

He attributed Facebook's success to user control over information-sharing and said Beacon should have worked the same way.

"People need to be able to explicitly choose what they share, and they need to be able to turn Beacon off completely if they don't want to use it," he said. "The problem with our initial approach of making it an opt-out system instead of opt-in was that if someone forgot to decline to share something, Beacon still went ahead and shared it with their friends. It took us too long after people started contacting us to change the product so that users had to explicitly approve what they wanted to share."

Last week, Facebook allowed users to opt in. Now, the social networking site has provided a privacy control to turn the feature off entirely, Zuckerberg said.