Final answer:
The standard used by most digital certificates is X.509, which sets the format for certificates and includes critical security details and the digital signature of the issuing authority.
Step-by-step explanation:
The standard used by most digital certificates is X.509. This standard defines the format for public key certificates which are used to establish a secure connection over the internet. It specifies, among other things, the standard fields for certificates and how they can be used to verify the identity of the certificate holder.
Digital Certificates functioning under the X.509 standard contain information such as the certificate holder's name, a serial number, expiration dates, a copy of the certificate holder's public key, and the digital signature of the certificate-issuing authority.