The Schengen Treaty erases the borders in the old continent and allows the citizens of 26 countries not to have to undergo controls in order to move around this whole area.
We must remember that not all the countries of the Union are in Schengen, as is the case with Ireland. But being Community citizens, they are included in the freedom of movement. As we have seen, the United Kingdom is also continuing to function as a country of the Union until the end of the year.
Another peculiarity is that there are states that are not in the Union and are in this territory, Switzerland, Norway, even Iceland. The doors have been opened to all these countries.
To clear up doubts, the European Commission has launched a tool in which we can consult the travel restrictions in the European Union. The tool is called Re-open (https://reopen.europa.eu/) and it consolidates a fundamental reference point for anyone moving within the Union.
It centralizes updated information from the Commission and the Member States in a single tool. It provides specific information on each of the EU Member States through an interactive map presenting up-to-date information on applicable national measures as well as practical advice for visitors to the country.