The Schengen Agreement
With a Schengen visa, you may enter one country and travel freely throughout the Schengen zone without showing your passport or a visa. Internal border controls have disappeared - it used to be that you would have to produce a passport and stop at international borders within the Schengen zone. Not any more! Now the border between two countries in Europe is nothing more than a signpost on the side of the highway, just like in the USA between states. Air, road and train travel are handled as domestic trips and EU residents do not even need to bring a passport.
The name "Schengen" originates from a small town in Luxembourg where in June 1985, the then seven European Union countries signed a treaty to end internal border checkpoints and controls. More countries have joined the treaty in succeeding years until today. Presently, there are 15 Schengen countries, all in Europe - but not all in the European Union!
The 15 Schengen countries are:
All these countries except Norway and Iceland are European Union members.