The Schengen Area is a group of 26 European countries that have abolished passport and immigration controls at their common borders. The Schengen Area consists of twenty-two Member States of the European Union (EU) and four European Free Trade Association (EFTA) member states. It functions almost as a single country for international travel purposes, with it's own common visa policy covering such things as short-term visits and some kinds of working visas.

Brief history
The Schengen Area was established based on the Schengen Agreement (named after the town in Luxembourg where it was signed) and led to the creation of Europe's borderless area in 1995. The treaty was signed on 14 June 1985 by five of the then ten member states of the European Economic Community. It proposed the gradual abolition of border checks at the common borders. Measures proposed included reduced speed vehicle checks which allowed vehicles to cross borders without stopping, allowing residents in border areas freedom to cross borders away from fixed checkpoints and the harmonization of visa policies.

Amendments
In 1990 the Agreement was supplemented by the Schengen Convention which proposed the abolition of internal border controls and a common visa policy. The Schengen Area operates very much like a single state for international travel purposes with external border controls for travellers entering and exiting the area, and common visas, but with no internal border controls.

Participants of the Schengen area
The Schengen Area currently consists of:

Austria
Belgium
Czech Republic
Denmark
Estonia
Finland
France
Greece
Hungary
Iceland
Italy
Latvia
Liechtenstein
Lithuania
Luxembourg
Malta
Netherlands
Norway
Poland
Portugal
Slovakia
Slovenia
Spain
Sweden
Switzerland


https://www.immigration-residency.eu/counsel/schengen-area/

Great job as always! Your posts are consistently insightful and enjoyable.