Data retention refers to all obligations on the part of data controllers to retain personal data for certain purposes.The Data Retention Directive (Directive 2006/24/EC (pdf)) contains an obligation for providers of electronic communications to retain traffic and location data of communications (e.g. through telephone, e-mail, etc.). Retention takes place for the purpose of the investigation, detection and prosecution of serious crime.

See also Council Framework Decision 2008/977/JHA.