On the Internet, nothing you say or do ever really disappears. We leave behind a trail of digital breadcrumbs everywhere we go. The fact that your behavior on the Web is being monitored by companies who want to utilize that info for their own interests isn't a big surprise, but the sheer size of the data footprint each of us accumulates may give you pause. In the end, they're using it to tailor-make a just-for-you Web experience that you're supposed to like—whether you like it or not.
It's the more alarming part of what author Eli Pariser, board president and former executive director of MoveOn.org, discusses in his excellent new book "The Filter Bubble," which, I should probably point out, I'm seeing ads for on a half dozen different sites I just visited. How did they know?
None of my friends are being shown the same ads because their search queries don't indicate that they'd be interested in the subject—their browsing is being affected by their own specific behavior. And it's not just happening with ads. That same concept of creating a personalized Internet experience applies to much of our browsing now, even basic Googling. There's no longer such a thing as standard search results. Instead we're shown a list of sites calibrated to best match the types of things it's assumed we'd want to know about.
Mr. Pariser writes in the book that "informational determinism,""invisible auto-propaganda" and personalization of the Web experience for each user combines for "a Web history you're doomed to repeat....a static, ever narrowing version of yourself—an endless you-loop." Or, in other words, the fact that you once searched "Morrissey lyrics" will haunt you for the rest of your digital life.
Whether you don't want companies to know which health problems you've been researching, or are just annoyed of being reminded about, say, a toaster oven you bought in 2006, a little Internet sweep-up is a good idea. Here are some basic steps you can take to help minimize your digital footprint:
Most browsers have options for private or incognito browsing. These modes make where you go on the Web less trackable, meaning that Firefox or Google will not save information about the sites you visit. Unfortunately it won't hinder third-party data collectors who vacuum up your data against your knowledge while you are browsing, but it's better than nothing. In Firefox you can select "Start private browsing" under "Tools." If you're using Chrome, click the wrench icon on your toolbar to open an "incognito" window.
Also consider using what are known as online anonymity systems like Tor (torproject.com). By routing your browser requests through a network of servers around the world, Tor makes it much more difficult for outside parties to track your Web habits or identify where your searches are coming from.
Disable Those Cookies
Cookies are the markers that companies leave on a browser to identify you. Sometimes this is helpful, as in when you want to keep a set of preferences every time you log in to a favorite site, but other times it has a more troubling intent. Disabling third-party cookies will help to stem the tide of outside companies using, trading and even selling the information gathered. In Safari, go to "Preferences," where you will find a padlock icon and a series of choices of whom to accept cookies from. Select "Block cookies from third parties and advertisers." In Firefox, under "Preferences," click on the "Privacy" tab and tweak the cookie and history options.
Get Some Privacy Add-Ons
Instead of going under your browser's hood, download add-ons at privacychoice.org to do the heavy lifting. TrackerBlock helps regulate which companies can collect information about you, and PrivacyMark will do its best to eliminate those pesky ads that are targeted specifically to you.
Tweak Your Google Settings
If you're worried about Google keeping track of everything you've searched for, there's a quick fix: Under "Settings," go to "My Account," then "Dashboard." Scroll down to "Web History" and click on "Remove items or clear Web history." Some people like the fact that Google keeps track of your searches because it helps create better results, others do not. To tweak your privacy level under your Google account (which anyone who uses Gmail has), go to your "Google Accounts" page and click on "My Account." From there you'll find "Authorizing Applications & Sites" where you will see third party sites you've granted access to. You can then choose to "Revoke Access" to any of them.
Tighten Facebook Privacy
Facebook is one of the first places companies look for data on people. It makes sense, as it's the place where we most freely share that information. By default Facebook encourages you to make things public, so crank up the privacy settings. You'll find the "Privacy Settings" page under the "Account" pull-down at the top right of the page. Inside are a huge number of options that let you customize the way your behavior on Facebook is shared with other users. You can also choose to remove your profile from Google search results, which will help cut down on people you don't know accessing your profile.
People take for granted that they have privacy on their home computer. "Every time you want to leave a site, log out if you can, otherwise whatever you were last doing is going to 'follow' you. That's how these ads work," says Jackie Cohen, editor at AllFacebook.com. That's true whether it's Amazon, Facebook, Google or many other sites. "Never just click away from Google," advises Ms. Cohen. If you're logged on through your Gmail account you can expect the searches you're making to be connected to your profile. That sort of fix may not completely strike everything from the record, but it will help do the next best thing: make it easier for you to forget they ever existed...even if the Internet itself never really does.