https://www.etiasvisa.com/etias-requirements/americans
U.S. citizens travelling to Europe will shortly need to apply for an ETIAS (European Travel Information and Authorisation System), the new travel authorisation for Europe that will come into effect in May 2023. ETIAS will help improve border management and boost security.
This means that, from May 2023, all Americans travelling to a European country in the Schengen zone will need an ETIAS. The Schengen Area is composed of European Union countries like France, Italy, Germany, Sweden, and Spain, as well as 4 non-EU countries: Iceland, Lichtenstein, Norway, and Switzerland. ETIAS will permit visa-free travel to all Schengen countries for short stays during its validity.