Schengen Area
The Schengen Area is an area without internal borders, an area within which citizens, many non-EU nationals, business people and tourists can freely circulate without being subjected to border checks. Since 1985, it has gradually grown and encompasses today almost all EU States and a few associated non-EU countries.
The link address is: https://ec.europa.eu/home-affairs/what-we-do/policies/borders-and-visas_en