Every time you open a browser to view a Web page, that information is stored on your computer—whether you're shopping online, checking movie listings, or catching up on the latest news.

Windows operating systems store this material in temporary Internet files or "cache." Web pages may store bits of information about who you are in files called "cookies" on your computer. Your Web browser will store a list of Web sites you've visited and places you've gone in a history file in your computer—thus creating your digital footprint. Even if you're not online, programs will store histories of the files you've opened, played, or viewed.

Cookies are created to recognize users when they return to a Web site; they make it possible to offer customized content to a user. Even though cookies make Web use quicker and more convenient, they can be a threat to your privacy if they store sensitive information like your name and password on protected login pages, preferences, account information, and choices you have made on the site. So, even if you clear browser history, cookies—like a map—can show your surfing preferences, habits, passwords, and so forth.

Even if the cookies don't contain such information, they clearly show that you visited the sites from which they came.

Unfortunately, many consumers don't understand the risks of digital footprints.

The problem, as Internet privacy experts have documented, is a growing one. Mary McFadden, writing in her 2007 Pew Research report, "Digital Footprints: Online Identity Management and Search in the Age of Transparency," perfectly captured the potential for peril in online ID fraud. "Unlike footprints left in the sand at the beach, our online data trails often stick around long after the tide has gone out," she says.

Few Web users bother to cover those footprints. According to the Pew Research study, only 3% of Internet users say they make a regular practice of reviewing their Web footprint, while 22% say they search using their name "every once in a while." Even worse, the vast majority of Web users aren't even sure what personal data they're leaving behind on the Web.

How do you leave footprints?

• Using search engines—The typical Web engine search reveals a lot to Web detectives. Your wants, needs, interests, careers, and financial life all can be revealed by your search habits. A search for a car loan on Google, for example, reveals a great deal about your financial health, your consumer sentiments, and even your future buying decisions.
  Your wants, needs, interests, careers, and financial life all can be revealed by your search habits.

• At work—Search engines and Web sites now have the technology to easily scoop up personal information based on your e-mails, browsing patterns, visits to chat rooms or blogs, even if related to your career.

• Social networks—The big Web search engines cast a wide net over who's visiting Facebook.com or MySpace.com. The same goes if you're a regular visitor to Yahoo's ubiquitous user communities or the chat room of other Web sites. These sites can tell a lot about your interests and habits—whom you chat with, what your hobbies are, and whom you talk to online.

• E-commerce— Any time you enter a credit card number or even a phone number during an online purchase, someone is storing it to build a record about your consumer habits—or worse.

• Web ads—Online advertisements are like big fishing nets, collecting your personal data like name, phone number, and e-mail address, every time you click on them.

• Web broadcast sites—You might think a trip to YouTube to watch Jay Leno's monologue from last night is pretty innocent. On the surface it is. But Google, which owns YouTube, collects a load of digital footprints from Web broadcast visits.

Protect your privacy

Here's how to lessen your digital footprint:

• Use Clear All History to delete cookies in Internet Explorer, Mozilla, Mozilla Firefox, Netscape, and Opera Web browsers.

• When you log in to a site and the computer asks whether you want it to remember you or if it's a public computer, choose public computer—even if you're using your home PC. This makes it more difficult for someone to retrieve personal information about you. It's more convenient to pick "remember me," but also more risky.

• Leave your name out of search terms. Don't search for your name, or your address, your corporate biography, or any of your personal information because the next person who uses the computer will be able to tell where you've been. If you have to conduct your own name search, use a different computer than the one you normally use—there's not as much of your personal history on your local library's desktop PC.

• Ignore your ISP. A lot of people rely on their internet service provider (ISP) to run their search engine tasks. Don't do it. Since your ISP is a part of the family, technologically speaking, and knows your search history, it will link your current searches to your previous ones, often into a single, easy-to-track search history. Example: AOL subscribers should not use http://search.aol.com to conduct their Web searches.
  Your Web browser will store a list of Web sites you've visited and places you've gone in a history file in your computer—thus creating your digital footprint.

• Try "Browzar." A new Web search engine called Browzar might be a Web visitor's best friend. The site acts as an online vacuum cleaner that removes Internet caches, histories, cookies, and online autoforms (the online tool that anticipates the Web address or search engine term based on data you've previously entered online and is stored on the browser).

• Consider purchasing software programs that help eliminate your digital footprint such as McAfee, says Dorothy Steffens, vice president of Web services for the Credit Union National Association, in Madison, Wis.

Published July 11, 2008