The number of people living on an island may gradually increase for a few simple reasons:
- More babies are born: When more babies are born than people who die, the population grows.
- People move to the island: People may come to live there for work, school, or family.
- People live longer: Better food and healthcare can help people stay healthy and live longer.
So, the island’s population grows when more people are born or move in than leave or die.