Web advertisers are stealthily monitoring our browsing habits—even when we tell them not to
In July 1993, The New Yorker published a cartoon by Peter Steiner that depicted a Labrador retriever sitting on a chair in front of a computer, paw on the keyboard, as he turns to his beagle companion and says, “On the Internet, nobody knows you’re a dog.” Two decades later, interested parties not only know you’re a dog, they also have a pretty good idea of the color of your fur, how often you visit the vet, and what your favorite doggy treat is.
How do they get all that information? In a nutshell: Online advertisers collaborate with websites to gather your browsing data, eventually building up a detailed profile of your interests and activities. These browsing profiles can be so specific that they allow advertisers to target populations as narrow as mothers with teenage children or people who require allergy-relief products. When this tracking of our browsing habits is combined with our self-revelations on social media, merchants’ records of our off-line purchases, and logs of our physical whereabouts derived from our mobile phones, the information that commercial organizations, much less government snoops, can compile about us becomes shockingly revealing.
Here we examine the history of such tracking on the Web, paying particular attention to a recent phenomenon called fingerprinting, which enables companies to spy on people even when they configure their browsers to avoid being tracked.
Cookies are small pieces of text that websites cause the user’s browser to store. They are then made available to the website during subsequent visits, allowing those sites to recognize returning customers or to keep track of the state of a given session, such as the items placed in an online shopping cart. Cookies also enable sites to remember that users are logged in, freeing them of the need to repeatedly provide their user names and passwords for each protected page they access.