The code consists of twelve characters: a two-letter country code of issuance, a nine-digit part identifying the issue, and a check digit. It is assigned by an authorized national agency.
The difference from a ticker is fundamental. A ticker is a short designation for trading on a specific exchange; it is convenient but may be the same for different instruments on different platforms. ISIN is unique globally and is used in settlements, record-keeping, and international transactions.
The code is assigned to a specific issue, not the issuer. One company will have different codes for common and preferred shares and a separate code for each bond issue differing in maturity and coupon.
Practical value for an investor is precise identification. When working with multiple issues from one issuer, when transferring securities between depositories, and when reconciling a statement with an account, relying on this code is more reliable than on the name or ticker.