The account number is the standardised code that allows us to identify it, easily access certain data (the country and the bank it comes from, the branch, the office from where it was opened, etc.). It's like a car number plate.
Before 2014, this account code was equivalent to the customer account code and had 20 digits. In 2014, globalisation and the extension of financial transactions beyond our country required cross-border payments to be made in an agile and secure manner. For this reason, the customer account code was replaced by the IBAN (International Bank Account Code), which is used to unify all transactions, issue and receive transfers in the Single Euro Payments Area (SEPA).