A financial institution number, or FIN, is a series of digits used to identify a banking institution during an inter-bank transaction, says WiseGeek. FINs possess a number sequence that identifies a bank, and a number sequence that identifies the particular branch. The combination of these two numbers allows the bank on the receiving end to readily identify the source of the transaction.
WiseGeek elaborates that financial institution numbers may vary in length across the globe per based on each country's national banking standards. Many countries produce FINs that are no longer than three digits. The financial institution number is also a fundamental component of the routing transit number, which is the number used by several countries to identify both the institution and geographic location of origin. In countries that use routing numbers, such as the United States and Canada, the placement of the FIN within the routing number may differ. This number, along with the account number, is vital to the successful transfer of money from one bank account to another.
An account holder in a country that uses routing numbers may find this information as the first sequence of numbers on the bottom, left hand side of a personal check. The U.S. Social Security Administration advises that if an account holder is not able to locate this information, he should directly contact the branch of his bank.