Watford is a town and borough in Hertfordshire, England, situated 20 miles (32 km) northwest of central London and within the bounds of the M25 motorway. The borough is separated from Greater London to the south by the urbanised parish of Watford Rural in the Three Rivers District.

Watford was created as an urban district under the Local Government Act 1894, and became a municipal borough by grant of a charter in 1922. The borough had 79,726 inhabitants at the time of the 2001 Census. The most recent official estimates put the population of Watford at 79,600 at mid-2006.