In computer networks, is the act of confirming the claimed identify of a system user by use of a password, or a password along with a second piece of information that is difficult for anyone else to know (two factor authentication), or a digital certificate.
A digital certificate is also known as a public key certificate, which is an electronic document issued by a certificate authority to prove ownership of a public key. Where private keys are held to encrypt traffic, the public key certificate authenticates that the public key has not been stolen e.g. by a man in the middle.
The process of authorization (see RBAC and ACL) is distinct from that of authentication. Whereas authentication is the process of verifying that you are who you say you are, authorization is the process of verifying that you are permitted to do what you are trying to do.