Table of Contents:
SSL Process
X.509
Signature
Fingerprint
Certificate Format
Client Certificate

A digital certificate, also known as a public key certificate, is used to cryptographically link ownership of a public key with the entity that owns it. Digital certificates are for sharing public keys to be used for encryption and authentication. Digital certificates include the public key being certified, identifying information about the entity that owns the public key, metadata relating to the digital certificate and a digital signature of the public key created by the issuer of the certificate. The signature signs the whole contents of certificates.

Most digital certificates in use today follow what is known as the X.509 standard.

Reference:
https://searchsecurity.techtarget.com/definition/digital-certificate