The origin of money could be traced back to the early days of human existence in which they (human beings) provided virtually all they needed through exchange of goods. This earliest form of trade/exchange is known as BARTER SYSTEM.
Barter therefore, is a system of trade in which money was not used rather goods were exchanged directly for other goods. For instance, one can exchange his Garri (a bag) for foul, which he cannot produce, with some other person who is willing to exchange his foul for a bag of garri. This system makes trade difficult.
However, because of the inherent difficulty/problems encountered in barter system, It was dropped and after then emerged the various other media of exchange such as Cowries, Manilas, Shells, Gold, Silver, Cattle etc before the emergence of currency (notes! paper money).