The document discusses different types of migration including international, emigration, immigration, internal, and circulation. It defines migration as the movement of people across boundaries to establish a new residence for at least one year. Migration can be caused by both forced and voluntary factors and occur on regional, national, or international scales. People migrate due to push factors like physical, environmental, economic, social, or political conditions in their origin as well as pull factors like opportunities at their destination, but intervening obstacles like restrictions, costs, cultural differences, lack of information or skills can influence people's ability or decision to migrate.