Also known as: communications metadata · traffic analysis
Metadata is the information surrounding a communication rather than its content — who contacted whom, when, for how long, from where, and how frequently — which remains visible even when the content itself is encrypted.
Metadata is often more analytically valuable than content precisely because it is structured. Content requires interpretation; metadata is a clean social graph ready for automated analysis, revealing relationships, routines, and affiliations without anyone reading a word.
Its legal protection is generally weaker than content protection in most jurisdictions, and it is retained by providers who cannot see message content. This is why metadata minimisation, rather than encryption alone, has become the focus of privacy-oriented protocol design.
Knowing that someone contacted a divorce lawyer, then a locksmith, then a bank, all within one hour, reveals a great deal without any message content being read.
End-to-End Encryption
End-to-end encryption (E2EE) is a system in which messages are encrypted on the sender's device and decrypted only on the recipient's, so that no intermediary — including the service provider — can read the content in transit or at rest on its servers.
Data Minimization
Data minimisation is the principle that an organisation should collect and retain only the personal data actually necessary for a stated purpose, and no more, for no longer than needed.
Surveillance
Surveillance in the privacy context refers to the systematic monitoring of individuals' communications, movements, or behaviour, whether conducted by states for security purposes or by companies for commercial ones.
Anonymization
Anonymisation is the process of altering data so that individuals can no longer be identified from it, either directly or by combining it with other available information — as distinct from pseudonymisation, which only replaces identifiers with reversible tokens.