Head of state succession
Head of state succession is the process by which nations transfer leadership of their highest office from one person to another. The succession of a head of state can be brought about through various means, the most common of which include:

Death of the current head of state
A military coup d'état against the present government
A general election
A vote of no confidence by the national legislature
Hereditary succession or appointment by a pre-determined council
Resignation (usually of a president)
Impeachment (usually of a president)
Abdication (usually of a monarch)