The London taxicab driver is required to be able to decide routes immediately in response to a passenger's request or traffic conditions, rather than stopping to look at a map, relying on satellite navigation or asking a controller by radio. Consequently, the "Knowledge of London" is the in-depth study of a number of pre-set London street routes and all places of interest that taxicab drivers in that city must complete to obtain a licence to operate a black cab. It was initiated in 1865, and has changed little since.