An IBAN contains information that can be used to determine your account number, the country of origin of your bank, and other account details.
When you make a payment, the code is compared to the IBAN registry to ensure that the beneficiary is correct.
If an IBAN is entered into the system without a connected account, the transaction will fail. If a matching account exists, the transfer will be completed, and it can only be modified with the recipient's official approval.
In fact, several banks use an IBAN checker, also known as an IBAN lookup, to ensure that legal IBANs are error-free.