We must immediately note that our standard image of surveillance—a person, generally representing the state, watching or listening in to the full stream of another person’s life—is unhelpful for various reasons. Today it is generally corporations, not the state, doing the tracking. The medium of corporate tracking is unlike a human sense (seeing or listening). It is, instead, the accumulation of data from multiple sources, what scholars have called “dataveillance.” At any one point in time, the surveiller is unlikely to have a full “picture” of the surveilled; only over time and through aggregation does a sufficiently detailed picture accumulate to motivate action. Finally, as noted in chapter 4, the target of surveillance is not the whole person but rather a montage of data doubles that probabilistically identify a real individual.

Nick Couldry & Ulises A. Mejias, The Costs of Connection, loc. 471