X money - earn extra income

The use of barter-like methods may date back to at least 100,000 years ago.

While standard of deferred payment is distinguished by some texts particularly older ones, other texts subsume this under other functions. A "standard of deferred payment" is an accepted way to settle a debt – a unit in which debts are denominated, and the status of money as legal tender, in those jurisdictions which have this concept, states that it may function for the discharge of debts. When debts are denominated in money, the real value of debts may change due to inflation and deflation, and for sovereign and international debts via debasement and devaluation.