Prisoner security categories in the United Kingdom

In the United Kingdom, prisoners are divided into four categories of security. Each adult is assigned to a category according to their crime, sentence, the risk of escape, and violent tendencies. The categories are designated with the letters A to D, with A being the highest level of security, and D the lowest.

There are three different prison services in the United Kingdom, and separate services for the three Crown Dependencies, i.e., the Channel Islands jointly and the Isle of Man. His Majesty's Prison Service manages prisons in England and Wales, and also serves as the National Offender Management Service for England and Wales. Prisons in Scotland are managed by the Scottish Prison Service and prisons in Northern Ireland are managed by the Northern Ireland Prison Service.