The banking identifier that identifies a bank branch in the United Kingdom is a sort code.
A UK sort code is a six-digit number usually written as three pairs, such as 12-34-56. It identifies the bank and branch associated with a UK payment account and is commonly used with an account number for domestic transfers and direct debits.
A sort code is not an international account identifier. International payments may require an IBAN and a BIC or SWIFT code, depending on the countries and payment systems involved.
Sort codes have also been used in Ireland and other systems influenced by British banking practice, but requirements differ by jurisdiction. Customers should use the account details supplied by their bank rather than infer a code from a card number.