Who can migrant?

Answer 1

Do you mean who can migrate?

If so, in the EU anyone can migrate to one country to another, as long as both countries are in the EU. Elsewhere, people who are the subject of or have fear of persecution on account of race, religion, nationality move country. They are called asylum seekers. When asylum seekers are granted permission to stay in the country by the government, they become refugees. Other valid reasons to move would be familial links, so they can live with their family.