If you are a citizen of a Schengen Area country, you can travel across most of the European Union without a passport, provided you carry a valid National Identity Card. This biometric ID card is legally sufficient for crossing borders and boarding flights within the Schengen Zone. However, for non-EU citizens (such as Americans, Canadians, or Brits), a passport is strictly required for all cross-border travel within the EU, even when moving between Schengen countries like France and Germany. While you may not always encounter a formal border booth, airlines and train operators (like Eurostar) will always require a passport for identity verification. In late 2026, the implementation of the ETIAS system will add a new digital layer for non-EU travelers, but it does not replace the physical passport. It is also important to note that EU countries outside the Schengen Zone (like Ireland) always require a passport for entry from other EU states. For the best security, every traveler in 2026 is advised to carry their passport regardless of the perceived "open" nature of the borders.