A ticker replaces the full name of the issuer when submitting orders and displaying quotes. It is assigned by the exchange and uniquely identifies a specific instrument within the trading platform.
It's important to understand that a ticker identifies not a company, but a security issue. One issuer may have different designations for ordinary and preferred shares, as well as separate codes for each bond issue. Choosing the wrong instrument is a common cause of purchasing the wrong security.
In addition to the ticker, there is an international identification number for securities used in settlements and accounting. The ticker is convenient for trading and can be the same across different exchanges, whereas the identification number is unique globally.
When working with bonds, relying solely on the issuer's name is insufficient: issues differ in maturity, coupon, and offer availability. Before submitting an order, you should verify the instrument code against the specific issue parameters.