Why would young people publicize the very information they want to keep private?

Critics argue that privacy does not matter to children who were raised in a wired celebrity culture that promises a niche audience for everyone. Why hide when you can perform? But even if young people are performing, many are clueless about the size of their audience. That's because the new generation is often proficient with technology it doesn't fully understand. The Carnegie Mellon study found that one-third of students don't realize that it is easy for nonstudents to access their Facebook profiles. And 30 percent of students did not even know they had an option to limit access to their profile.

Most people don't use the privacy settings to limit access to their Facebook profile. Four out of five simply accept the default setting, which allows their whole network to see the entire profile. In the UCLA network, that's 50,400 people. The Boston network has 312,404 people. For comparison, the city's tabloid, the Boston Herald, has a circulation of 201,503. Users may think they're only sharing with the friends they can see, but they're actually publishing with the reach of a newspaper.

Social networking sites also induce users to disclose information in order to be part of the site's culture. "Allowing users into your circle allows them to track your moves on Facebook and vice versa," explains technology writer Michael Hirschorn. "Even more compellingly, it allows you to track, if you wish, their interactions with other users, all from your own user page. You can play with your privacy settings to prevent this, but as you become acculturated to the site, you realize that you have to give information to get information."

Facebook's Kelly argues that the trend is broader than a single website. People know their actions are tracked online, he says, just as they're tracked on streets filled with surveillance cameras, "whether privately controlled through an ATM or publicly controlled [for] legitimate anticrime or anti-terrorism purposes." In an era of massive top-down surveillance, posting information on a website may feel downright redundant. Just as most consumers have acquiesced to companies collecting loads of data and private information about them, many Facebook users seem resigned to the company's aggressive use of private information.

In September Facebook launched a "public search" feature to list users' profiles on search engines like Yahoo! and Google. The move could fundamentally shift the site from a (relatively) closed social network to a more exposed public directory. Students originally joined Facebook as a private campus hub, but now it touts some of their profile information to the world. (Diligent users can opt out, and visitors still need to be Facebook members to view people within networks.) The massive search function might one day make Facebook an indispensable part of Internet commerce--creating the "Google of people," as blogger Jeff Jarvis puts it. The potential loss of privacy could ultimately beat the feed controversy by several orders of magnitude, but there has been no backlash so far.

Ultimately, these privacy concerns do not turn on the decisions of one social networking company like Facebook, or what its future owners may do. The architecture of these sites already facilitates all kinds of surveillance of unsuspecting users by the public. Employers check Facebook to vet job applicants, for example, and some have advised users to change their profiles or photos during the application process, as the Stanford Daily reported last year. A 2005 survey found that one out of four employers has rejected applicants based on research via search engines. Campus police increasingly review social networking sites to investigate crimes. Arkansas's John Brown University expelled a student after administrators discovered Facebook pictures of him dressed in drag last year, a violation of the school's Christian conduct code. And a Secret Service officer paid a dorm visit to University of Oklahoma sophomore Saul Martinez based on a comment he posted on the Facebook group Bush Sucks.

Even if this generation of Internet users is truly developing a "new privacy" concept that prioritizes nuanced control, they largely fail on their own terms. Most users do not exercise any real authority over their information; they accept default exposure settings, post to huge networks and transfer ownership of their social media productions to entertainment businesses. Thus "control" devolves to the thousands of people in their networks and the business models of ambitious companies. The entire social network ecosystem, with its detailed records, pictures and videos of formative years, can completely change on a company's whim. Most users are left relying on the kindness of strangers and the benevolence of business.

A simple way to address one of Facebook's privacy problems is to ensure that users can make informed choices. Taking a page from the consumer protection movement, Congress could simply require social networking sites to display their broadcasting reach prominently when new users post information. Just as the government requires standardized nutrition labels on packaged food, a privacy label would reveal the "ingredients" of social networking. For example, the label might tell users: "The photos you are about to post will become Facebook's property and be visible to 150,000 people--click here to control your privacy settings."

This disclosure requirement would push Facebook to catch up with its customers. After all, users disclose tons of information about themselves. Why shouldn't the company open up a bit, too?

Facebook's invisible audiences should also stop hiding. Responsible institutions that choose to monitor users (and minors) on the site, such as schools and employers, have a special obligation to inform users and parents of the practice.

In the end, social networking sites are wildly popular precisely because they disseminate information so effectively. Posting to a network is easier than e-mailing individuals, and usually more fun. One bright side is that these sites' popularity dispels the recurring complaint that the web is merely an incubator for like-minded people to isolate themselves, associating only with the people and ideas that confirm their beliefs. Young people are doing just the opposite. Their favorite websites are about real people in the real world--not just their like-minded best friends but hundreds of acquaintances from different facets of their lives.

The problem, of course, is that playing with reality online is riskier than playing with video games and anonymous screen names. Young people are recording their lives in minute detail, enabling unprecedented experiences, exposure and evidence that will outlast their youth. Social networking is a free service, but abdicating control of personal information, photos, writing, videos and memories seems like a high price to pay.