Upvote:7
It is strictly regulated in the Schengen Border's Code which passport must be stamped and which must not be stamped when crossing an external Schengen border. Some countries deviate slightly from the regulation, particularly for residence permit holders, but in general:
- Passports of EU and EEA citizens must not be stamped. If the border guards follow the regulation, they will not even stamp your passport if you ask for it.
- In general, but with some exceptions, passports of non EU/EEA citizens must be stamped both on entry and exit. There is no Schengen wide database with electronic records of entries and exits, so the border guards need to rely on the stamps to check if the passport holder has not exceeded the allowed duration of stay in the Schengen area. Such a database (Schengen EES, Entry/Exit System) is planned to go into operation next year.
UK is already operating a database with all entries and exits, so they do not need to stamp your passport anymore to keep track of the time you spend in the country.