Liquid asset. Liquidity describes the ease with which an item can be traded for something that you want. Money is the most liquid asset because it is universally recognized and accepted as the common currency. In this way, money gives consumers the freedom to trade goods and services easily without having to barter (senza barattare).
A causative factor in the economy. It affects inflation and money supply.
Controller of the economy. Monetary policy: decisions about interest rates can affect production, unemployment, etc.