Tourists normally use zone 1 where most of the tourist attractions are located, along with a lot of the popular hotel districts. Some of London's trendy neighbourhoods like Camden and Notting Hill are located in Zone 2.
Within London, all London Underground, National Rail, London Overground, TfL Rail and Docklands Light Railway stations are assigned to six fare zones. Fare zone 1 covers the central area and fare zones 2, 3, 4, 5 and 6 form concentric rings around it.
Central London is zone 1, zone 2 is the ring around zone 1, zone 3 is the ring around 2 and so on. If you look at the zone map below it should make sense. *zones 7,8 and 9 cover a small area just outside North West London including Watford, Croxley Green, Rickmansworth, Amersham or Chalfont & Latimer.
Zone 2 training is typically the lowest zone used for training purposes. Think of it as going for a jog while you can still hold a conversation – somewhere between 60-70% of your maximum heart rate. The purpose behind Zone 2 training is to be able to sustain a pace just below your aerobic threshold for 30+ minutes.
A Travelcard gives you unlimited travel within London zones 1-4 or 1-6 on the Underground, Overground, TfL Rail, Docklands Light Railway, buses, trams, and most National Rail services in London*.
Zone 2 training, often referred to as aerobic training, is characterized by a low-to-moderate level of cardiovascular exertion and power output that can be maintained for a substantial amount of time. Think of an 'easy run' or a moderate bike ride.
Hyde Park Corner is a London Underground station near Hyde Park Corner in Hyde Park. It is in Travelcard Zone 1, between Knightsbridge and Green Park on the Piccadilly line.
Zone 1: An area in which an explosive gas atmosphere is likely to occur in normal operation; Zone 2: An area in which an explosive gas atmosphere is not likely to occur in normal operation and, if it occurs, will only exist for a short time.