A program that prevents other malicious programs from entering a computer or a network for the purpose of unauthorized data collection or other malicious purposes.
Glossary
The process of verifying that an entity (e.g. a user) is who they say they are. Authentication allows systems to be kept secure by ensuring that only authenticated users or processes can access them. There are several authentication methods. For general users, one of the most common is a username-password combination called single-factor authentication, but nowadays more and more services use two-factor authentication, which requires additional information (e.g. code sent via SMS) for authentication. Authentication precedes authorisation.
The process of assigning process or access rights to an identified user or device. During authorisation, the appropriate permissions are continuously checked. For computer systems, administrators can specify in detail what a particular user can access and at what level, and also what actions they can perform. Logically, authorization comes after authentication.