You may not realize it, but as you surf the Web, you're being tracked. When you search on Google and click through to a result, Google knows what you clicked — and the site you visit knows you came from Google.
That's not all, though. By using cookies, which are small amounts of data stored on your hard drive, websites can track you across the entire Web. For example, when you visit site A, a cookie is stored on your hard drive. Then when you visit site B hours, days, or weeks later, it can read that cookie and know you visited site A.
It's not the websites that are tracking you, though — it's the ads! If you visit a site that sells sports equipment and there's an ad on that site, that ad provider now knows that you like sports equipment. Later, if you watch a Michael Jackson video on YouTube and the same ad provider appears on that page, it knows that you like sports equipment and Michael Jackson! Basically, as you surf the Web, ad companies are creating a profile of your habits, your pastimes, and your likes and dislikes.
The result of this is targeted advertising, in which ads seem to know a scarily large amount of information about us.
Fortunately, if you don't like the idea of being tracked, there are some great ways to avoid it with Internet Explorer, Firefox, Chrome, and Safari.
Internet Explorer 8 (IE8) comes with a built-in tool called InPrivate Filtering. By simply turning it on, IE8 will prevent your surfing habits from being transmitted to third-party companies when you visit websites.
You can enable it temporarily by clicking Tools, InPrivate Filtering, and then "Block for me." Unfortunately, there's no easy way to enable it permanently — but if you're fairly confident at navigating around your computer, check this guide, which will walk you through the process in very easy steps.
Another option is to use Simple Adblock, an Internet Explorer 8 add-on. Not only does it stop ad companies from tracking you, but it also removes almost every ad from websites you visit.
If you use Firefox, you have access to the most popular add-on in the world: Adblock Plus. It stops every ad from displaying and prevents tracking at the same time.
If you merely want to prevent tracking, try Ghostery, which shows who's tracking you and lets you easily block them.
Chrome, like Firefox, relies on add-ons to block third-party tracking cookies. Keep My Opt-Outs comes straight from Google and blocks cookies from most big, U.S.-based ad companies. Google intends to add blocking for other territories, but for now, if you're not in the United States, AdBlock is probably your best bet.
There's also Disconnect, which is very highly rated, though it seems like it only blocks a handful of companies.
By default, Safari actually blocks these third-party tracking cookies, making an additional add-on unnecessary. Still, if you want finer control over which cookies are blocked, look no further than Safari Cookies.
If you want to enable third-party tracking (some people prefer targeted advertising — it's less likely to be boring!), click Safari, then Preferences. Click the Security tab and toggle "Accept cookies" to Always.
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