As our lives increasingly move to the digital realm – whether it’s what we read, what we watch, photos that once sat in frames now uploaded to a server farm somewhere in the rural United States, or even the 140-character thoughts we share with the world ­­– comes the very reconstitution of our identities online. A German artist named Tobias Leingruber recently took this concept to its logical extreme when he produced physical identification cards based on Facebook profiles (this attempt at satire was executed so well that Facebook sent Leingruber a cease-and-desist letter three days later).

Between the lines of Leingruber’s satire, though, is a very real, emerging concept. What Leingruber hit on is something I refer to as social currency. Social currency essentially refers to the idea that every person has an online identity formed through participation in social networks, websites, digital communities, and online transactions. Our everyday activities — web searches, status updates, ‘likes’, tweets, and comments — they all leave a trail of data behind which we tend to see as ephemeral or throwaway.
TechCrunch