Blue signifies that the countries are Schengen Area members, light blue have open borders, and orange are obligated to join.
The Schengen Area refers to 26 European Union member states that have abolished passport and border control, functioning as a single country for travel purposes, having a common visa policy. Cyprus, Romania, Bulgaria, and Croatia wish to join the area and are obliged to, while the United Kingdom and Ireland refused to join the area. By 22 March 2016, after the November 2015 Paris attacks and the ongoing European migrant crisis had shown the weaknesses of the system, Austria, Belgium, France, Denmark, Germany, Norway, and Sweden tightened border security to monitor the influx of migrants from the Middle East and Africa.