World's states coloured by systems of government: Parliamentary systems: Head of government is elected or nominated by and accountable to the legislature.
Presidential system: Head of government (president) is popularly elected and independent of the legislature.
Presidential republic
Hybrid systems:
Semi-presidential republic: Executive president is independent of the legislature; head of government is appointed by the president and is accountable to the legislature.
Assembly-independent republic: Head of government (president or directory) is elected by the legislature, but is not accountable to it.