EU member states participating
EU member states participating, but with land border controls still in force
EU member state not participating but obliged to join
EU member state with an opt-out
non-EU member states participating
non-EU member states de facto participating
non-EU member states with an open border
The Schengen acquis is a set of rules and legislation, integrated into European Union law, which regulate the abolition of border controls at the internal borders within the Schengen Area, as well as the strengthening of border controls at the external borders.