Usually multiple forms of ID. In Australia you have a "points" system (each form of ID is worth a certain number of points and they are additive) where you need

Usually multiple forms of ID. In Australia you have a "points" system (each form of ID is worth a certain number of points and they are additive) where you need 100 points to create a bank account. This translates to a drivers license and passport, or drivers license and existing debit card, etc. In Estonia I believe the system is based on public key cryptography (every national ID has a private key that is used for signing things).