What is "southend-on-sea"

Southend-on-Sea , commonly referred to as simply Southend, is a seaside resort town and wider unitary authority area with borough status, in Essex, England, on the north side of the Thames estuary east of central London. It is bordered to the north by Rochford and to the west by Castle Point. It is home to the longest leisure pier in the world, Southend Pier. London Southend Airport is located north of the town centre.