What is a certification authority (CA) ?
A certification authority is an organization that issues digital certificates.
A digital certificate is the cyberspace equivalent of an identity card and is used to assign a particular public key to a person or organization.
This assignment is certified by the certification authority, by providing them with its own digital signature.
The certificates contain "keys" and additional information that is used for authentication and for encryption and decryption of sensitive or confidential information that is distributed over the Internet and other networks.
As additional information, for example, lifespan, references to certificate revocation lists, etc. are included , which are introduced by the CA within the certificate.
The purpose of a certification institution is to issue and check such digital certificates. The CA is responsible for the provision , allocation and for securing the integrity of the issued certificates it issues .
Thus it is an important part of the public-key infrastructure.