Migration is the movement of people from one place to another.
The reasons for migration can be economic, social, political or environmental.
Migration impacts on both the place left behind, and on the place where migrants settle.
Internal migration is when people migrate within the same country or region - for example, moving from London to Plymouth.
International migration is when people migrate from one country to another - for example, moving from Mexico to the USA.
Emigration - when someone leaves a country.