To ensure a separation of powers, the U.S. Federal Government is made up of three branches: legislative, executive and judicial. To ensure the government is effective and citizens' rights are protected, each branch has its own powers and responsibilities, including working with the other branches.
Separation of powers, therefore, refers to the division of government responsibilities into distinct branches to limit any one branch from exercising the core functions of another. The intent is to prevent the concentration of power and provide for checks and balances.