Some basic characteristics can be used to distinguish between the two systems. The relationship between the executive and legislative branches is one of the defining features. In a presidential system, the president is popularly elected, either directly or indirectly, and holds office for a fixed term. The legislature cannot remove the president from office, except by impeachment . Conversely, in a parliamentary system, the executive is named by the legislature, on which he or she depends for continuance in office. The national executive encompasses the dual roles of head of state and head of government. In a presidential system, these two roles—the first a ceremonial one representing the nation and the second the administrator of the government—are joined in a single person. In a parliamentary system the two are separated, with one person, sometimes a monarch, serving as head of state.