Your digital footprint is all the stuff you leave behind as you use the Internet. Comments on social media, Skype calls, app use and email records- it's part of your online history and can potentially be seen by other people, or tracked in a database.

"It is impossible to overlook the extent to which civilization is built upon a renunciation of instinct," Sigmund Freud said. There's always a tension between how much we should follow our instincts and how much we should yield to social conventions.