Tracking the quantified self [Technically speaking]

Self-tracking is not really a tool of optimization but of discovery, and if tracking regimes that we would once have thought bizarre are becoming normal, one of the most interesting effects may be to make us re-evaluate what "normal" means. For better or for worse, we are data-generating machines. Whenever we pay with a credit card or drive through an automated toll system, or answer an e-mail or make a phone call, we can't help but leave a steady stream of ones and zeroes in our wake. This is our digital exhaust: the trackable or storable actions, choices, and preferences that we generate as we go about our daily lives.