What form of government includes a king or queen as the head of state?

A monarchy is a form of government where a single individual, usually a king or queen, serves as the head of state. This system often includes a royal family and can be characterized by hereditary leadership, where the position is passed down through generations. In a monarchy, the monarch typically has varying degrees of power; in some cases, they may hold significant authority over the state's governance, while in others, their role may be largely ceremonial, with actual political power residing in elected officials or a parliament.

In contrast, a republic is a government system where the head of state is elected, and leadership is generally associated with elected representatives rather than a hereditary figure. An oligarchy focuses on a small group of individuals in power, often based on wealth or social status, while democracy emphasizes the participation of the entire populace in the decision-making process, with elections and equal representation. Each of these systems differs fundamentally from a monarchy, where the continuity of leadership is based on lineage rather than public election or selection.