a.k.a. digital shadow, data exhaust, electronic footprint
An expression that refers to the way technology now pervades everyone's lives, your "digital footprint" specifically describes the trail you leave in cyberspace and on any form of digital communication.
For example, New York Governor Eliot Spitzer resigned after being caught on a federal wiretap arranging to pay a high-priced prostitute. Detroit's mayor, Kwame Kilpatrick forgot the depth of his digital footprint when he sent romantic text messages to a staffer. The mayor of Arlington, Oregon, Carmen Kontur-Gronquist was voted out of office after she left unrestricted lingerie-clad images of herself on her MySpace page.
It is now widely accepted that in this era of e-mail, texting, blogging, and social networking, trying to hide one's digital footprint is practically futile. In fact, it's been reported that the FBI can hear your conversation via your cell phone even when it is turned off (the only thing to thwart this is take out the battery).
Unlike paper trails, which can ultimately be destroyed or eliminated, "digital paper trails" are recorded and stored at remote locations that you may not even be aware of, and to that degree, there is nothing you can do to erase these records. An example is when Google's search results were subpoenad as evidence in court to help convict a man of murder because they revealed his past Internet searches, which included information on the murder weapon and learning how to murder someone in exactly the same manner as his wife was killed. (Click on the link below to watch the "Big Brother" video for more on that story.)
Most people don't need to worry about murder or re-election, but improper activities can also cost you your job (see: dooce). The message is to be careful when you open the drapes because any kind of digital dirt could get you in trouble. The advice is to either not engage in improper activites or only communicate about such activites in person, in real time, F2F.