A digital certificate helps prove the identity of a website, server, or person and can support encrypted connections.
A signed identity statement
A certificate binds a public key to a name and is signed by a trusted certificate authority. Browsers use it as part of deciding whether a secure connection belongs to the requested site.
Trust has an expiry date
Certificates include validity periods and may be revoked. A valid certificate does not make a website honest; it mainly helps establish the identity of the endpoint holding the key.