In general, deflation is when an entire economy's total currency supply or price level of goods and services steadily decreases. It is the opposite of inflation. The maximum amount of Bitcoin that can be issued was set at 21 million BTC which is set to be reached by the year 2140. The amount issued each year is also set to decrease, which combined with an increase in the number of people using Bitcoin, will increase its value. The expected deflation of the Bitcoin network is intended to maintain its safety and ability to be self-contained.