Prior to the creation of money, individuals and firms had to accept other goods or services as payment, or be self-sufficient by producing everything required

Often lacking self-sufficiency or driven by the desire for a wider range of goods/services, bartering became the norm but it too had problems

As individuals and firms trade with each other in order to acquire goods or raw materials, they require a means of exchange that is acceptable and easy to use 

Modern currency fulfils this purpose and money functions as a medium of exchange, a measure of value, a store of value, and a method of deferred payment