It is not a stand-alone organisation, but a part of the Ministry of Defence (MOD). The organisation employs civilian and military staff. The organisation was formerly known as the Defence Intelligence Staff or DIS, but changed its name in 2009.
Defence Intelligence gets information from many sources. This information is used to support military operations, planning, and defence policy. It notes politico-military, scientific and technical developments which may affect the UK. DI's assessments support the work of the Joint Intelligence Committee (JIC), other Government departments, and international partners such as NATO and the European Union.
It is this 'all-source' information which distinguishes Defence Intelligence from other organisations such as SIS and GCHQ. They focus on the collection of 'single-source' human intelligence (HUMINT) and signals intelligence (SIGINT) respectively.