I do not know if it’s true for all countries, but at least the USA and the UK require your passport to be signed to be valid. And I know that when I fly, I sometimes get checked if it is signed.
Is there a practical reason for this? Does the signature get checked against anything? Or is it simply that the law says a passport must be signed to be valid, so there you go?
I googled around a bit, but only found resources on how to sign, but not why it needs to be signed.
Thank you Internet hive mind!
The theory is that you’ve signed your passport and it’s on a type of paper that will visibly deform if you try to erase it or white paper over it - so in theory a border guard could ask for your signature and compare it to the one on the document as a proof of identity.
In the modern world this doesn’t really matter because we’ve got a lot better ways to authenticate - including databases with your signature already in them.
However, the tradition lives on.
Oh also, it’s always a good idea to get someone to sign something if they’re doing fraudulent stuff - since it’s absolutely trivial to prove a forged signature done in front of a witness in court… it’s like getting Capone for tax fraud - easy to prove cases are easy.