Records showing the full website addresses you have visited — for instance, www.gchq.gov.uk/what_we_do — are treated as content. But the first part of an address you have visited — for instance, www.gchq.gov.uk — is treated as metadata.
In isolation, a single metadata record of a phone call, email, or website visit may not reveal much about a person’s private life, according to Ethan Zuckerman, director of Massachusetts Institute of Technology’s Center for Civic Media.
But if accumulated and analyzed over a period of weeks or months, these details would be “extremely personal,” he told The Intercept, because they could reveal a person’s movements, habits, religious beliefs, political views, relationships, and even sexual preferences.
For Zuckerman, who has studied the social and political ramifications of surveillance, the most concerning aspect of large-scale government data collection is that it can be “corrosive towards democracy” — leading to a chilling effect on freedom of expression and communication.
“Once we know there’s a reasonable chance that we are being watched in one fashion or another it’s hard for that not to have a ‘panopticon effect,’” he said, “where we think and behave differently based on the assumption that people may be watching and paying attention to what we are doing.”