Final answer:
X.509 is an international standard for digital certificates used in computers and technology. It was first issued in 1988 and contains information about the owner and a signature from a trusted third party, or Certificate Authority.
Step-by-step explanation:
X.509 is an international standard for the format and information contained in a digital certificate. It is the most common type of digital certificate in the world. It was first issued on July 3, 1988.
A digital certificate is a digital document that contains a public key signed by the trusted third party, which is known as a Certificate Authority, or CA. X.509 certificates are relied on by S/MIME and contain your name, information about you, and the signature of the person who issued the certificate.