A study a few years ago by computer scientists at Stanford University shows just how often personal data can be harvested on sites that you visit. An article from the New York Times about the study notes that “[y]our online travel — your clickstream, as it’s poetically known — is not always anonymous. It can often be traced right back to rather precise parts of you, including your name and e-mail address.”
The article discusses other studies showing similar issues relating to the way that your trail of personal data can be gathered and repurposed in all sorts of ways without your ever being aware of it.
How worried should we be?
Sengupta, Somini. “Stanford Researcher Finds Lots of Leaky Web Sites.” New York Times. New York Times, 11 Oct. 2011. Web. 25 Feb. 2013.