What Can They Find Out About You?

Your IP address is sent to every web site you visit. While no one can determine your exact street address directly from your IP address, there are ways to infer this information with elaborate tracking schemes. Think of your IP address as a serial number, a unique identifier some web sites can use to identify you when you visit.
For instance, let’s say you make a purchase from an online store that sells toasters. As soon as you pay for that fancy new four-slicer, the store records your name, street address, credit card information, and your IP address. Provided the toaster store keeps your private information private, you’ve got nothing to worry about. But can you say the same thing for the other site you just used to sign up for a free plasma TV?
This is where advertising comes in. Most ads on many web sites originate from only a handful of companies, and those companies track who’s looking at their ads, even when you don’t click them. If you view a page at a news web site that displays a banner ad hosted by, say, adknowledge.com or targetnet.com, and then you sign up to win a free TV on another site that has another ad from the same agency, that ad server knows you’ve visited both sites. What’s more, if the ad agency is in cahoots with the people who are giving away the TV, they have your email address, street address, shoe size, and anything else you typed into the sweepstakes sign-up page.
Now, most folks have dynamic IP addresses, which change every time they start a connection, but a single IP can remain active all day (or with a router, for weeks at a time), which means your IP address can be used to track quite a bit of your online activity. And with a geolocation tool like http://www.yougetsignal.com/, anyone can find your approximate location. What’s more, many unscrupulous sites use so-called tracking cookies to do the same thing—namely, tag your PC with a unique serial number that can be read as you visit many different sites. So, how can you stop the snooping? Most antispyware software is designed to scan your system and delete any tracking cookies it finds, but you may want to take it one step further and configure your browser to not accept any cookies from these sites. You can get a list of known tracking sites from http://www3.ca.com/securityadvisor/pest/browse.aspx?cat=Tracking%20Cookie. (If this feels like overkill, block only those sites responsible for the cookies your antispyware software finds on your PC). To block cookies in Internet Explorer, go to Tools ? Internet Options, choose the Privacy tab, and click Sites. In Firefox, go to Tools ? Options, choose the Privacy category, expand the Cookies section, and then click Exceptions. Or, in SeaMonkey, go to Tools? Cookie Manager? Manage Stored Cookies.
Next, install ad-blocking software such as the Adblock extension described in “Stop Annoying Animations,” and use a proxy server to mask your IP address.