Keynesianism, or Keynesian School, is a political-economic doctrine that defends the state as an active agent against recession and high unemployment.
The ideas of Keynesianism emerged with economist John Maynard Keynes, mainly from the publication of his book "The General Theory of Employment, of Interest and the Currency" in 1936.
After the New York Stock Exchange (1929), Keynes thought that the solution would be to re-expand the economy through new government spending, which would make it possible to create jobs.
With this, the State would take an active role, reaching the so-called Full Employment, scenario where there is only a certain natural unemployment and out of the state of crisis.