Cookies and IP addresses alone may not give away your personal information, but when these clues are combined with other Web surfing data -- like your search history -- you could unwittingly disclose your identity to hackers, scam artists or government investigators.
Search engines routinely store search queries associated with your IP address. Google stores search queries for nine months and MSN stores them for 18 months [source: Privacy Rights Clearinghouse]. By examining hundreds or thousands of search queries from the same IP address, it's possible to deduce someone's identity, particularly if they have done map searches on their home address or entered their Social Security number.
Another threat to online privacy involves Web e-mail accounts. If you use the same Web site for both your e-mail service and Internet searches, you might be leaving a very clear trail for hackers and cybercriminals to follow when you go online.
For example, if you use Google as your e-mail provider, then you need to log in to Gmail.com for each e-mail session. Any Google Web searches you conduct while logged in to your e-mail account will be associated with the same IP address as your e-mail account. From there, it would be easy for a hacker or other third party to associate your searches with your e-mail address -- and to use this information to send you customized spam or other e-mail scams.
The simplest and most direct way for someone to track your Web surfing is to view the history on your Web browser. Your Web browser keeps a chronological list of every Web site you visit. Most Web browsers will save your browsing history for at least a week by default. If someone wanted to monitor your Web surfing, all that person would have to do is open your browser and search your history.
If you're surfing the Web from a work computer, your boss doesn't need to physically turn on your computer and check your browser history. Since you're working on an office network, your employer has the right to monitor what sites you are visiting.
In the next section, we'll talk about anonymous proxy servers, one of the most effective ways to hide your identity online.