Macroeconomics - Wikipedia

... represents the rise of prices over time.

The average price for a cinema ticket is around $10 right now. How much was it back in the 50s? About 50 cents.

The story goes a little deeper than this, but one thing to remeber is that governments usually target an yearly inflation rate of about 2%. It may seem counter-intuitive to target price increases, but on a large scale, these have been deemed to drive the economy. 

After the US Great Depression of the 30s, J.M. Keynes came up with Keynesian economics.

His theory, centered around aggregate demand and its influence over the overall level of economic activity, lead to the introduction of various fiscal stimulus schemes, which can theoretically, for example, pull an economy out of a recession.

Keynes' ideas were disputed by some, including by Nobel laureate M. Friedman, who argued that a small, constant expansion of the money supply is the right approach of handling an economy over interefering in major ways.

He is associated with monetarism and the Chicago School of Thought.

Monetary policies deal with regulating the supply of money. These can influence inflation or bank interest rates.

Fiscal policies, on the other hand, deal with taxes and government spending.