India's recent move toward a cash-free society helped reveal just how important physical currency is to the informal economies that the poorest families depend upon.
You can now pay your way with apps, cryptocurrencies and other digital alternatives. Physical money might one day look like a relic of the past.
ATMs began appearing in churches providing a way for people to come up with ready cash to give to God and their church. But why was cash necessary?
What's on your cash? Studies show our money carries everything from pet DNA and old food to E.coli and traces of cocaine.
Currency first hit the scene thousands of years ago. An anthropologist explains the early origins and uses of money – and how archaeological finds fill in our picture of the past.
Fifty years after the first ATM went into service, the main problem – identifying authorized users – remains the same. But methods for doing so have improved significantly.