Original: For example, when the king or queen of a hereditary monarchy dies or abdicates, the crown is usually passed to the next generation, i.e, his or her child, typically in some order of seniority.
Simplified: When the king or queen of a hereditary monarchy dies or quits the throne (abdicates), the crown is generally passed to one of his or her children, often to the oldest. When that child dies, the crown will be then passed to his or her child, or, if he or she has no child, to a sister, brother, niece, nephew, cousin, or some other relative.