(CNN) everyone knows Hong Kong as the buzzy island city home to over seven million people perpetually on the move. But it may be a surprise to learn that many of the residents this bustling city don't spend much time foraging in their pockets for change, especially on transport.Insted, they whip out their octopus, a contactless smart card with a chip that communicates with a fare processor in less than a second. It has been in use in Hong Kong since 1997.