  We review the quantum version of a well known problem of cryptography called
coin tossing (``flipping a coin via telephone''). It can be regarded as a game
where two remote players (who distrust each other) tries to generate a
uniformly distributed random bit which is common to both parties. The only
resource they can use to perform this task is a classical or quantum
communication channel. In this paper we provide a general overview over such
coin tossing protocols, concerning in particular their security.
