In the context of computer systems, authentication is a process that ensures and confirms a user’s identity. Authentication is one of the five pillars of information assurance (IA). The other four are integrity, availability, confidentiality and non repudiation.
Authentication is the process of determining whether someone or something is, in fact, who or what it declares itself to be. Authentication technology provides access control for systems by checking to see if a user's credentials match the credentials in a database of authorized users or in a data authentication server.