The common name London may appoint several different geographical or administrative units, which can sometimes lead to confusion.
The most common use refers to the Greater London, one of the nine regional subdivisions of England, formed of the territory under the authority of the Greater London Authority and the Mayor of London. Greater London is regarded as a NUTS-1 region within the European Union. It is this set of approximately 1600 km2 for 7.5 million inhabitants which is commonly referred to when speaking of the British capital. Greater London is divided into two areas; Inner London and Outer London. Both areas are considered NUTS-2 regions. However, Greater London is not officially a city, whose status, strictly defined in the UK, is awarded to a city by the British monarch on specific criteria. Before its creation in 1965, the territory of Greater London was part of the counties of Kent, Middlesex, Surrey, Essex and Hertfordshire.
The City of London (abbreviated City, or Square Mile in reference to an area of 1 square mile), in the heart of Greater London, is the historical definition of London. This is where the modern city was born and today is the oldest district of the capital. It is also a full-fledged district with special status. The City of London and the rest of Greater London form two parts of different “Lieutenancy” (Lieutenancy areas).
The vast London agglomeration can be described by the urban region of London, which corresponds to the zone occupied by the suburbs, which occupies a territory roughly similar to the Greater London but with a slightly higher population. Beyond the urban area is the London urban area (London commuter belt or London Metropolitan Area) which includes the territories inhabited by people traveling daily (commuters) to work in London. The urban area of London has grown considerably during the Victorian era and again during the interwar period. Its expansion was stopped in 1940 because of World War II and the policy known as the Green Belt and its area has not changed much since. The boundaries of the Metropolitan Police District and the catchment area of London transport have evolved over time but today correspond approximately to that of Greater London.
Other terms such as Inner London, Outer London, Central London, North London, South London, East London, East End of London, West London or West End of London are sometimes to designate neighborhoods, statistical units or districts of London.
Unlike many other capitals, the status of “Capital of the UK” of London has never been officially granted to the city by decree or written charter. His current position is established by constitutional convention, London being the seat of British power. Its status as de facto capital is in fact an element of the unwritten constitution of the United Kingdom. The capital of England was moved to London from Winchester after the Norman conquest.
Perhaps the Romans marked the center of Londinium with the London Stone, still visible in Cannon Street 7. The coordinates of the center of London (traditionally located in the Eleanor Cross at Charing Cross, near the corner of Trafalgar Square and Whitehall) are approximately 51° 30′ 29″ N 0° 07′ 29″. Trafalgar Square has also become a central place of celebration and demonstration.
Translated from Wikipedia