Colchester is a city located in north-eastern Essex, England. At the 2021 census, the built-up area of the city had a population of 130,245, making it the second-largest settlement in the county of Essex after Southend-on-Sea.
The city serves as the namesake for the wider Colchester local government district, which encompasses an extensive surrounding area. Residents of the city are referred to by the demonym Colcestrian.