Alphanumeric codes are combinations of letters and numbers used to represent information in a concise format. These codes can include uppercase and lowercase letters, digits, and sometimes special characters. They are commonly used in various applications, such as creating passwords, product identifiers, and serial numbers, making it easier to categorize and manage data. One popular example of alphanumeric codes is the ISBN (International Standard Book Number), which uniquely identifies books. Another example is license plates, which often combine letters and numbers to identify vehicles. Alphanumeric codes enhance security and organization in digital and physical systems.