These two channels influence features such as economic growth and employment, and are generally determined by the central bank and the government (e.g., the United States Congress) respectively.
[1] It is generally posited the policy mix should aim at maximizing growth and minimizing unemployment and inflation.
Both can have other objectives and must adhere to some constraints – obeying a deficit rule, securing the financial sector, courting popularity, etc.
Monetary policy is typically carried out by the central bank, which controls interest rates and the money supply to balance the outcomes for inflation and unemployment.
Central bank independence is generally held to be positive, because it prevents a single authority from simultaneously issuing debt and paying it off with newly created money, which would be inflationary.