Dacorum is a local government district with borough status in Hertfordshire, England. The council is based in Hemel Hempstead. The borough also includes the towns of Berkhamsted and Tring and surrounding villages. The borough had a population of 155,081 in 2021. Dacorum was created in 1974 and is named after the ancient hundred of Dacorum which had covered a similar area. The borough of Dacorum is the westernmost of Hertfordshire's ten districts. It borders St Albans, Three Rivers, Buckinghamshire and Central Bedfordshire.

Hertfordshire is a ceremonial county in the East of England and one of the home counties. It borders Bedfordshire to the north-west, Cambridgeshire to the north-east, Essex to the east, Greater London to the south and Buckinghamshire to the west. The largest settlement is Watford, and the county town is Hertford.