The concept of a credit-card size piece of plastic containing digital cash is already familiar.
Several systems are just about to be launched after extensive trials.
But once significant amounts of commercial activity take place using digital cash, a number of economic effects are likely to be felt. The figure in 1995 was 22.3bn. On a smart card, it hasn't actually moved. It is still the bank's money, right up till you spend it, and it transfers to the account of the payee. And the bank can use it and earn interest on it.