What are a digital certificate and a certification authority (CA)?

A digital certificate is an electronic file signed by a certification authority that confirms the identity of a person, company or website and serves encryption, authentication and electronic signature; a certification authority is a trusted entity that issues, renews and revokes such certificates, for example X.509.

* From application to revocation: how a certificate is issued, used, checked and withdrawn. *

Swiss law (ZertES) calls the CA a provider of certification services; umbrella terms are Zertifizierungsstelle, trust service provider and Vertrauensdiensteanbieter. Synonyms for the certificate: identity certificate, public-key certificate.

Go deeper:

• Public key certificate (Wikipedia) — what a certificate contains and the types in use.
• Certificate authority (Wikipedia) — how CAs issue, sign and are themselves trusted.