A certificate number is a unique identification number assigned to a certificate, which is printed on the certificate itself. The certificate number is used to identify the certificate and the person to whom it was issued. Examples of certificates that may have a certificate number include birth certificates, drivers licenses, and certificates of naturalization. In the medical field, certification numbers relate directly to an individual and their certification in a given field, along with any additional skill sets. In some cases, such as with sustainable financial instruments, a certification number may indicate that a specified instrument was issued, invested, established, created, or granted certification.