A president is the head of state of a republic. Presidents are usually appointed democratically, either by being directly elected or by being chosen by elected representatives of the people, although some unelected dictators also use the title. From the second half of the twentieth century onwards, as the colonial era came to an end, most newly independent countries chose to appoint a president as part of their new constitution. Countries without presidents tend to be older monarchies, where the role of head of state is instead filled by the king or queen. Countries in the Commonwealth do not have a president, since their head of state is the Queen of Great Britain and Northern Ireland.