Related factors of international migration

Since the entry of foreigners is a controlled activity, citizenship naturally becomes one of the main information registered by relevant departments, and another key information is the purpose of entry. These two factors, namely, citizenship and entry purpose, determine different stay periods. According to the legislation and practices of various countries, we can divide immigrants into visitors, tourists or immigrants according to the length of stay. In addition, other important information on which immigration statistics are based is the country of residence and the country of birth.