Facebook is set to begin rolling out a site-wide overhaul to its privacy controls, a process that will require all of its more than 350 million users to update their personal settings that govern how their information is shared across the network.

Beginning later today, when users visit the site, Facebook will greet them with a privacy announcement page that offers an overview of the changes and prompts them to navigate to their privacy settings page.

Users can click a button to skip the step, but Facebook officials said that when they log in again after 24 hours they will be required to update their privacy controls.

The changes, announced last week by CEO Mark Zuckerberg, aim to simplify Facebook's elaborate privacy settings, while also giving users more granular control over who has access to the information they post on the site.

Elliot Schrage, Facebook's vice president of communications and public policy, told reporters on a conference call this morning that the update is a shift to "a new, simpler model based on contextual privacy where users control the privacy over every single thing they share."

He added, "We believe that people should have the ability to share information with only the people they want."

The operative change dispenses with Facebook's regional networks as the underpinning of its privacy framework. The system that is being phased out would set as a default a person's self-identified network, which could be a large city or even an entire country, as the boundary for access to updates to the site.

As the site's popularity has soared, those networks have grown apace, meaning that a person's default privacy settings would make personal information available to millions of strangers.

Facebook is now rolling out a feature called publisher privacy control, which enables users to determine how widely available each update they make to the site before it is posted. A drop down menu will offer users the choice of sharing content with categories defined as friends, friend of friends or everyone, meaning the information would be publicly available to anyone on the Web, not just members of the community. Facebook will also offer a custom setting.

Users under the age of 18 will not have the option to share content with everyone.

After users are prompted to update their privacy settings, they will be directed to a listing of the various categories of information, such as work and education details, photos and contact information, and specify the sharing parameters for each. Facebook will provide suggestions for each setting, but will recommend that users who had already customized their privacy controls carry over the old settings.

Company officials estimated that between 15 percent and 20 percent of the site's users had previously taken the time to adjust their privacy settings.

Kenneth Corbin is an associate editor at InternetNews.com.  Based in Washington, D.C., Kenneth's coverage areas range from government regulation to e-commerce and online media.