[Phil Lelyveld comment: Although this article is about the NSA, it explains how Google and other companies can know everything about you.]
Metadata collection can answer all but one of the five “W’s” of journalism: the Who, What, Where and When. Given time, it can even respond to “Why” someone interfaces with digital information systems the way they do. It can do this because it is possible to discern patterns of behavior in metadata.
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