Migration = movement.
Human terms: Change of home.
It can be temporary, seasonal and daily.
Permanent international migration: Movement of people between countries.
Emigrants: People who leave a country
Immigrants: People who arrive in a country.
Migration balance: Difference between numbers of emigrants and immigrants.
Countries with a net migration loss loose more people by emigrants than they win with immigrants.
Countries with a net migration gain receive more people by immigration than they lose by emigration.
Asylum seekers are people who have left their home country, have gone to another country to be recognized as a refugee and are awaiting a decision on their application.
Illegal immigrants: Enter a country with no belongings, no personal documents (passport) and fail to meet the legal requirements of the country and become part of the hidden economy. They rely of local people that bring them food, work and shelter. This leaves them vulnerable for exploitation.
Economic migrants: They make a conscious choice to leave their home country knowing that they can return there if they wish without problems. They move to have a better job, improve their standard of living and quality of life.
Counterurbanisation: Process by which people and employment move away from the cities and conurbations to smaller settlements, because of:
Employment: An industry might move from inside the city to edge-of-city sites, or to smaller rural towns. People move because of promotion, for better paid jobs, or simply to find a job.
Housing: Affluent people are likely to want a bigger house, more comfortable and with garden and garage.
Changing family status: People move because of an increase on family wealth or family size.
Environmental factors: People move away to escape from the noise, air and visual pollution. They move to find quietness.
Social factors: Prejudice against neighbours, or to avoid local crime, vandalism and poor...