Monetarism is an economic theory that emphasizes the role of governments in controlling the amount of money in circulation. It suggests that changes in the money supply have significant effects on national output and inflation. Monetarists believe that managing the money supply is crucial for maintaining economic stability and growth. The theory gained prominence in the 1970s, largely due to the work of economist Milton Friedman. Monetarists argue that excessive money supply growth leads to inflation, while too little can cause unemployment and slow economic growth. They advocate for a steady, predictable increase in the money supply to promote a stable economy.