Facebook has responded to privacy concerns by announcing simplified privacy controls and applying them retroactively, so users can protect the status updates and photos they have posted in the past.
"A lot of people are upset with us," CEO Mark Zuckerberg acknowledged at a news conference at Facebook's Palo Alto, California., headquarters.
The changes came after Facebook rolled out a slew of new features in April that spread its reach to the broader web.
Among them was a program called "instant personalisation" that draws information from a person's profile to customise sites such as the music service Pandora.
Privacy groups have complained to regulators, and some people threatened to quit the site. Even struggling MySpace jumped in to capitalise on its rival's bad press by announcing a "new, simpler privacy setting."
To address complaints its settings were getting too complex, Facebook will now give users the option of applying the same preferences to all their content, so that with one click you can decide whether to share things with just "friends" or with everyone.
For those who found it complicated to prevent outside websites and applications from gaining access to Facebook data, there's now a way to do so in a couple of clicks.
It's not clear whether the changes will quell the unease among Facebook users, which has threatened to slow the site's breakneck evolution from a scrappy college network to an internet powerhouse with nearly a half-billion people.
"They've lost the users' trust. That's the problem," said Marc Rotenberg, executive director of the Electronic Privacy Information Centre. "In the earlier days, there was time to regain it. It's not so clear now. I think it's getting more serious than making changes and moving on."
Before the announcement, Craig Mather, a 28-year-old graduate student in Portland, Oregon, was already complaining of having to adjust his privacy settings every time Facebook came up with a new plan.
"It puts us on our guard, where we feel like we are trying to plug a leak," he said.
For Luke Finsaas, who is 24 and has been using Facebook since college to keep in touch with friends and family in Australia, whether the site's vision works out in the end is a matter of trust.
"It's incredibly brilliant but wildly terrifying," he said.
"Google has been around for a while, and we know that they are pretty serious about privacy and protecting us. We know that they've got our back. But Facebook has had privacy issues in the past."
Google has struggled with its own privacy issues - most recently with its Buzz social media experiment and, particularly in Europe, with sending cameras into cities to take photos for its Street View map feature.
But users feel a deeper connection with Facebook, where they exchange not just messages and 140-character tweets but news of major life events and newborn baby photos.
That means privacy concerns are heightened, too.
"Facebook wants to be the social centre of the Web, and any social interaction that takes place on the Web they want to be in control of," said Debra Aho Williamson, a senior analyst at research firm eMarketer.
"If its plan succeeds, that could be a big problem. They will have access to too much information."
What's changing
• Facebook currently gives users granular controls over many of the things they share on the site, such as each photo and status update. With the changes, users will be able to apply the same settings to everything with one click, so that they can share with friends, friends of friends or everyone. But for those who want them, the granular controls are staying.
• There is less information that Facebook makes automatically public. You can now hide your home town, for example, and the pages for hobbies, books and other interests that you have linked to your profile. These were previously visible to everyone.
• Facebook says it will stop updating its privacy settings so frequently.
• Users can now turn off all outside applications and websites, instead of having to deny them access one by one.
• As it rolls out the changes, Facebook plans to notify users through a message that will appear on their page when they first log in.
• The changes apply retroactively, as well as to new services still to come.
What's not changing
• Users' full name, profile picture, gender and work or college networks remain visible to everyone.
