The Entry/Exit System (EES) is an automated IT system for registering non-EU nationals travelling for a shorty stay, each time they cross the external borders of any of 29 European countries using the system.
For the purpose of the EES, 'non-EU national' means a traveler not holding the nationality of any European Union country or the nationality of Iceland, Liechtenstein, Norway or Switzerland.
'Short stay' means up to 90 days withing any 180-day period. This period calculated as a single period for all the European countries using the EEs, and the system will automate identification of travelers that have overstayed 90 days, possibly resulting in entry denial or forced exit.
If you are mistakenly registered in EES while traveling, please report the situation to your unit leadership. If you need help with an EES-related issue while at an airport or other external border crossing in the Schengen area, please contact the U.S. Embassy for assistance.