The Schengen Area is a group of 26 European countries that have abolished passport and immigration controls at their common borders and have a common visa policy. It functions almost like a single country for international travel purposes, which, while allowing participating countries to add their own specific provisions regarding types of residence and local visas, ensures that certain types of visas are universal and that the person holding a residence permit is in one Schengen country does not need a visa to visit or transit through another Schengen country - in that sense it is very close to the general immigration policy of the European Union (the United Kingdom and Ireland are part of their own separate agreement called (and therefore do not apply there Schengen rules, even if they are both part of the European Union (it should also be noted that the Schengen area also includes non-EU countries). https://www.immigration-residency.eu/real-estate/