The International Bank Account Number (IBAN) is a standardized system of identifying bank accounts across national borders, enabling international transactions to be processed accurately and efficiently. IBAN consists of up to 34 alphanumeric characters that uniquely identify a customer's bank account, including country code, check digits, and bank account details. When asking, "What is IBAN?", it refers to this unique identifier, crucial for cross-border transactions, ensuring that funds are transferred accurately to the intended recipient.