The London boroughs are the 32 local authority districts that comprise Greater London; each is administered by a London borough council. The present London boroughs, which are a type of local government district, were all established at the same time as Greater London on 1 April 1965 by the London Government Act 1963 and are the same as Greater London. There are twelve Inner London boroughs and twenty Outer London boroughs. The City of London, the city's historic core, is a separate ceremonial county and unique local government district that operates very differently than a London borough. Nonetheless, the two counties collectively comprise the administrative area of Greater London and the London Region, which are both governed by the Greater London Authority.
More on London postal districts here.