NEW YORK — In Facebook's vision of the Web, you would no longer be alone and anonymous. Sites would reflect your tastes and interests — as you expressed them on the social network — and you wouldn't have to fish around for news and songs that interest you.
Standing in the way is growing concern about privacy from Facebook users — most recently complaints that the site forced them to share personal details with the rest of the online world or have them removed from Facebook profiles altogether.
Facebook responded to the backlash Wednesday by announcing it is simplifying its 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," chief executive Mark Zuckerberg, 26, acknowledged at a news conference at Facebook's Palo Alto, Calif., 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 personalization" that draws information from a person's profile to customize sites such as the music service Pandora. Some users found it creepy, not cool.
Privacy groups have complained to regulators, and some people threatened to quit the site.
To address complaints that 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, now nearly a half-billion in number.
"They've lost the users' trust. That's the problem," said Marc Rotenberg, executive director of the Electronic Privacy Information Center, an advocacy group. "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."
Some of Facebook's loudest critics offered cautious praise but indicated the young company will need to do more to prove it cares about privacy.
Sen. Charles Schumer called it a "significant first step that Facebook deserves credit for," but added he'd still prefer that Facebook require users to actively turn on sharing with outside sites, rather than having sharing be the default setting.
For Facebook, being seen as a company people can trust with the personal details of their lives is key. Users will share information only if they have control over who sees it.
Facebook's lifeblood is advertising. It makes money by letting businesses target ads to specific types of users — such as 30-year-old single men living in Brooklyn who are interested in motorcycles and yoga.
But convincing users that sharing more is good for them has at times been an uphill battle. Users revolted against Beacon, a feature that broadcast people's activities on dozens of outside sites when it launched in 2007. Facebook gave people more control over Beacon before scrapping the program completely as part of a legal settlement.
More recently, Facebook has come under fire for a security glitch that exposed some users' private chats, and another that revealed users' information to advertisers in a way they could identify them, going against Facebook's own terms of service.
"Facebook wants to be the social center 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."