Telecommunications data retention

In the field of telecommunications, data retention (or data preservation) generally refers to the storage of call detail records (CDRs) of telephony and internet traffic and transaction data (IPDRs) by governments and commercial organisations. In the case of government data retention, the data that is stored is usually of telephone calls made and received, emails sent and received and web sites visited. Location data is also collected.
The primary objective in government data retention is traffic analysis and mass surveillance. By analysing the retained data, governments can identify the locations of individuals, an individual's associates and the members of a group such as political opponents. These activities may or may not be lawful, depending on the constitutions and laws of each country. In many jurisdictions access to these databases may be made by a government with little or no judicial oversight (e.g. USA, UK, Australia).
In the case of commercial data retention, the data retained will usually be on transactions and web sites visited.
Data retention also covers data collected by other means (e.g. by automatic numberplate recognition systems) and held by government and commercial organisations.