to correct the OP
currency is anything used as a medium of exchange
That's not correct!
Currency is not ANYTHING used as a medium of exchange, you can use many things as a medium of exchange which I'm sure is obvious around you. You can purchase your shoe and other products and properties with gold or other products and properties, which makes your definition faulty.
Currency is rather a LEGAL TENDER (fiat) note and others backed by the central bank of a country.
to emphasise
currency is any form of medium of exchange.. sex is a form of currency..
when a mass community agree on a currency they call it money
a governments fiat is money..
the US governments money is USD(dollar) but USD(dollar) is not europeans money.. europeans recognise dollar as currency. but not THEIR MONEY
europeans money is EURO. americans money is not EURO but americans recognise euro as a currency.
there are subdivisions of terms.. learn them
a currency does not have to be fiat. but fiat currency is a currency.
bitcoin is not any governments money. bitcoin is OUR money. though other governments recognise bitcoin as currency
get it yet
if we wanna use it for ourself its our money. others not using it wont recognise it as money because they are not in the community that use it