The term for a government ruled by a king or queen is monarchy. In a monarchy, the monarch typically holds significant power and authority, which can be either absolute or constitutional. In absolute monarchies, the king or queen has complete control over the government and is not bound by a constitution. In constitutional monarchies, the monarch's powers are limited by a constitution or laws, with a parliamentary system in place. Monarchies can be hereditary, where the position is passed down through family lines, or elective, where leaders are chosen through various means. Historically, monarchies have played significant roles in shaping nations and cultures.