Note:
4 signatory states of the Schengen Agreement, which are not Member States of the European Union, respectively :
1) Island
2) Norway
3) Switzerland
4) Liechtenstein
2 Member States of the European Union, decided not to apply in full the Schengen acquis, but co-operates with Schengen Member States in certain fields, respectively:
1) Ireland
2) United Kingdom
In June 2013, Croatia became an EU member state and in 2015 notified its Declaration of readiness, in order to join the Schengen Area.