Short answers, pulled from the story.
The Maastricht Treaty came into force on the 1st of November 1993 to formally establish the European Union. Horst Köhler, Helmut Kohl, and François Mitterrand served as main architects of this historic agreement.
Robert Schuman stood before the French press on the 9th of May 1950 to announce a radical new plan for Europe that proposed placing French and German coal and steel production under a single High Authority. The Treaty of Paris signed in 1951 created the European Coal and Steel Community with members including Belgium, France, Italy, Luxembourg, the Netherlands, and West Germany.
By 2025, the union had grown to encompass twenty-seven member states with an estimated population exceeding four hundred fifty million people. Croatia joined as the twenty-eighth member state in 2013 but the current count stands at twenty-seven following departures like that of the United Kingdom.
The euro became official currency in twenty-one member states by 2025 after replacing national currencies starting in 2002. Three hundred forty-five million citizens now live within the eurozone covering most of western and southern Europe while the European Central Bank controls monetary policy for all participating nations.
The country officially departed from the union on the 31st of January 2020 after extensions granted during negotiations initiated under Article 50 on the 29th of March 2017. Most areas of EU law continued applying to Britain until the 31st of December 2020 during transition periods.