When more people start to live in cities, it's called urbanization. It happens when people move from the countryside to cities, when cities naturally grow faster, or when rural areas start to look more like cities, like when suburbs spread out. Urbanization in rich countries is beginning to slow down, with about 80% of people living in cities..

Examples: Picture New York City in the 19th century. It started as a small port town but grew rapidly due to industrialization, attracting people from the countryside for better job opportunities.

This is like a ride on a rollercoaster. First, people rush to cities (urbanization), then they spread out into suburbs (suburbanization), next they go back to the countryside (counter-urbanization), and finally, they return to the city (re-urbanization).

When more babies are born than people die, that's natural increase. It often happens in cities because younger people tend to live there. The countryside they leave behind tends to have older folks and fewer births.

Example: Take Lagos, Nigeria, which is one of the fastest growing cities in the world, largely due to its youthful population.

This is when people pack their bags and leave the countryside to live in cities. This happens because people think they'll be better off in cities.

• Push Factors - Things that make people want to leave a place (like not enough jobs or too many natural disasters).
• Pull Factors - Things that attract people to a new place (like more jobs or good schools).

Example: A farmer in a small village in India might move to Mumbai, pulled by the promise of better job opportunities and pushed by the lack of opportunities in his village.