In London, Hackney Carriage drivers have to pass a test called The Knowledge to demonstrate they have an intimate knowledge of London streets.
The first Hackney Carriages were licenced in 1662, and were at the time literally horse-drawn carriages. During the 20th century these were generally replaced with cars, and the last horse-drawn Hackney carriage was withdrawn from service in 1947.
The name derives not from Hackney in London, but from the French word haquenée, referring to the horse that was pulling it. The New York terms "hackstand" (taxi stand) and "hack license" (taxi license) likely derive from "hackney carriage."