"International migration plays an increasing role in most Member States. Immigration brings both economic and social opportunities and challenges to countries receiving immigrants ... [and it] is now at the forefront of European and national policy agendas. This issue looks at three categories of immigrants in the EU-27 Member States: nationals, citizens of other EU-27 countries, and non-EU citizens, with particular regard to their age, sex and country of citizenship ..." (Quoted from publication)