National central banks play an important role in the foreign exchange markets. They try to control the money supply, inflation, and/or interest rates and often have official or unofficial target rates for their currencies.

The printing of paper money was also associated with wars, and financing of wars, and therefore regarded as part of maintaining a standing army.

Trend is a term used to describe the persistence of price movement in one direction over time. Trends move in three directions: up, down and sideways. Trend indicators smooth variable price data to create a composite of market direction. Generally, the trend could be either UP, or DOWN, or TREAD (flat).