Currency is mainly the system or type of money which is used by a particular country. it is something that is used as a medium of exchange so that it can be traded for goods and services.
It is a form of money approved by the government and is used by the people of the country to buy goods and services as per their requirements. every country has its own currency for example India has the Indian rupee, the united state of America has dollars, and Canada has Canadian dollars.
In early times barter system was prevalent, in this goods and services were exchanged for goods and services. as the economy grew currency replaced the barter system and made money the only medium of exchange.