Summary. Facebook, Google, and a host of other websites and advertisers track your browsing habits using cookies and other methods. Usually this is to provide advertising that’s relevant for your likes and dislikes.
It’s almost creepy. You visit an online store, and soon begin to see ads for that store showing up on other sites you visit.
A mistake with website tracking systems is that they begin to show you ads for stuff you’ve already visited — instead of blocking ads from sites you’ve already visited, which would make more sense. If you’re already a regular online shopper at Sears.com, why waste advertising space on ads for them?
A story this weekend in the New York Times disclosed an alarming trend regarding consumer tracking:
“Your application for credit could be declined not on the basis of your own finances or credit history, but on the basis of aggregate data — what other people whose likes and dislikes are similar to yours have done. If guitar players or divorcing couples are more likely to renege on their credit-card bills, then the fact that you’ve looked at guitar ads or sent an e-mail to a divorce lawyer might cause a data aggregator to classify you as less credit-worthy. When an Atlanta man returned from his honeymoon, he found that his credit limit had been lowered to $3,800 from $10,800. The switch was not based on anything he had done but on aggregate data. A letter from the company told him, ‘Other customers who have used their card at establishments where you recently shopped have a poor repayment history with American Express.'” [source]
Your Digital Thumb Print. As companies become more savvy, it’s possible that aggregate data will provide a digital thumb print to track site visitors. For example, even with cookies turned off, all websites gather data about your IP address, your computer’s operating system, and the resolution of your screen. A constellation of data such as this could uniquely identify you as you move through the Internet.