Migration - from Latin - relocation . External migration - people moving it from one country to another with change of place of residence permanently or for a long period. In external migration distinguish emigration - exit from their country to another and immigration - enter the country of citizens of another state. In the population of the country affecting external migration, including immigration contribute to the mechanical growth of population. The difference between the number of emigrants and immigrants entitled net migration . It can be positive (in the case of predominance of people arrived) and negative if the number of those who left the country, more than the number who came to her.
External migration has always occurred. They played a great role in human development, particularly in shaping the population structure of many countries (U.S., Canada, Australia, South America, etc.). Causes of external migrations can be economic, political, religious, family and household, environmental, natural (associated with natural disasters - earthquakes, droughts, etc.). Economic factors are the main and primary cause of migrants worldwide. For economic reasons distinguish labor migration (job search) and outflow minds (search-paid intellectual work by scientists and people of creative professions).
important problem associated with external migration is the problem of refugees. About 20 million people have become in recent years forced migrants - refugees , due to international and inter-regional conflicts, civil wars, natural hardships, hunger and poverty. Each country anyway faces problems of migration, making migration policies. Depending on the demographics and needs of the economy, national governments encourage or restrict the arrival of foreigners.