The rise in online social networking, coupled with the evolution of advanced data-tracking techniques, has created a goldmine for internet marketers who now can target their advertising in highly sophisticated ways to individual web users. High school and college students are especially vulnerable, experts say, and that has many privacy advocates concerned. Now they're enlisting the help of Congress to set reasonable limits.

The web sites we visit, the online links we click, the search queries we conduct, the products we put in virtual shopping carts, the personal details we reveal on social networking pages--all of this can give companies an enormous amount of insight into our tastes and habits.

But privacy watchdogs warn that too many people have no idea that internet marketers are tracking their online habits and then mining that information to serve up targeted pitches--a practice known as behavioral advertising. High school and college-age students are particularly vulnerable to this practice, because of the long trail of data they reveal about themselves on web sites such as Facebook and MySpace.

So Congress could be stepping in. Rep. Rick Boucher, D-Va., chairman of the House Energy and Commerce Subcommittee on Communications, Technology, and the Internet, is drafting a bill that would impose broad new rules on web sites and advertisers. His goal: to ensure that consumers know what information is being collected about them on the web and how it is being used, and to give them control over that information.

While Congress has waded into internet privacy issues before, this measure could break new ground, as the first major attempt to regulate a nascent but fast-growing industry that represents the future of advertising. Boucher insists his bill will benefit consumers and preserve the underlying economics of the internet, which relies on advertising to keep so much online content free.

"Our goal is not to hinder online advertising," he said. "This will make people more likely to trust electronic commerce and the internet."

Although his proposal is still taking shape, Boucher is confident lawmakers will pass an online marketing privacy law of some sort. He is working with Cliff Stearns of Florida, the top Republican on the House internet subcommittee, as well as Rep. Bobby Rush, D-Ill., who chairs a separate subcommittee on consumer protection.

Already, Washington's interest in internet marketing has put online advertisers on notice. In July, the industry released a set of self-regulatory principles in an effort to head off concerns in Congress and the Federal Trade Commission. The FTC put out internet ad guidelines early this year.

Boucher's efforts have encouraged privacy activists, who point out that internet surveillance has evolved beyond just data-tracking files, known as cookies, that web sites place on visitors' computers. Technologies such as "deep packet inspection" now can monitor a user's every online move.