ATLANTA -- Lauren Shields didn't like the idea that her every move on the Internet might be tracked and reported to who-knows-whom, so she downloaded a free program to shut out the online trackers.
That's when the metro Atlanta seminary student found out just how many snooping eyes were upon her. With each website she visited, the new software showed her an alert, revealing which companies were recording her every click. Some had household names such as Facebook and Google; others she didn't even know.
''It's none of their business. That's my private life," said Shields, 30. "It means they are compiling a database on you -- where you go and who your friends are -- and I'm uncomfortable with that."
Shields represents a fast-growing demographic: people who are taking steps to thwart the industry that anonymously tracks their movements in the virtual world. That industry has spawned a counter-industry of companies that create free anti-tracking software. Several of the companies behind the best-known programs -- Ghostery, Adblock Plus and Do Not Track Plus -- reported major jumps in usage in 2011.
Adblock Plus has more than 17 million daily users, 5 million of whom downloaded the software within the past year, said managing director Till Faida. The company is expecting greater gains this year as it introduces programs for Android phones.
TrackerBlock has seen a rising interest in its service, with hundreds of thousands of people using it daily, said Jim Brock, founder of the parent company, PrivacyChoice. Ghostery is being downloaded by 140,000 new users each month, said Scott Meyer, head of the parent company, Evidon, a pace sufficient to double the number of users last year to 4.5 million.
''It's taking off. Consumers know they're being tracked, and this helps them control it," Meyer said.
As people live more of their lives online, from shopping on websites to socializing on Facebook, more and more of their personal habits can be tracked and translated into profit, said Mustaque Ahamad, director of the Georgia Tech Information Security Center.
Although companies that track such information say they are serving Web consumers by helping them receive ads tailored to their personal interests, he said, "many privacy-conscious people take issue with someone tracking their online activities without their consent."
Shields, who downloaded Do Not Track Plus six months ago, said she feared the widespread dissemination of her data would place her at risk of identity theft, and she worried about her private information finding its way to prospective employers.
''I'm not a techie, I just want to protect myself online," said Shields, who was referred to The Atlanta Journal-Constitution for this article by the software company.
The tracking of people's online behavior has become increasingly sophisticated. The tracking companies install, without a person's knowledge, a piece of code in their Web browser that allows the company to compile data on their preferences for websites. That information is often sold to marketers and advertisers, which explains why Web users see so many ads pop up that seem geared specifically to them.
Web-based marketers argue that, by generating more online sales, such activities underwrite the Internet itself, which brings users virtually unlimited information at no charge.
These days when Shields opens up a website, a small box appears in a corner of her screen, revealing the companies that are tracking visitors to that site. She can then choose to block those trackers; if she does, the computer "remembers" her instructions for future use.
Anti-tracking programs have existed for years, but the conventional software built into browsers can be difficult to use and end up blocking an entire website.
Tracking activities are legal and monitored by the Federal Trade Commission. The data that is shared is not tied to a person's name and does not include such identifying information as Social Security or credit card numbers, unless a person has agreed to disclose them, Meyer said.
However, he said, some critics take issue with the clarity of some websites' disclosure policies.
Rob Shavell, co-founder of Abine, which produces Do Not Track Plus, said he believes that some companies link the shared information in ways that expose a person's identity and personal information.
Fears abound that identifying data will be sold to credit companies, health insurers and even prospective employers.
''Who knows what's going to happen to this data in the future?" Shavell said. "It's just not a comfortable feeling."
Bryan Wilber of Atlanta, a computer program analyst who surfs the Internet almost every day, worries about the use of his data.
''You worry that some health insurance companies will be able to look at the data and know you order cigars on the Internet," said Wilber, 49.
But he's not about to download some free protection service he's never heard of, having seen the Internet ads for free anti-virus programs -- some of which turn out to be viruses.
The Internet privacy companies hope to make tracking protection as prevalent as anti-virus programs. Abine projects that its North American users will grow from 17 million to 28 million in the next year.
Shields said she likes not having to worry about the prying eyes of Big Brother, or, in this case, Big Brothers.
''I just don't want a giant company knowing that much about me," she said.
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