This document provides an introduction to information security concepts. It defines information security as protecting information and systems from unauthorized access, use, disclosure, disruption or destruction. The key aspects of information security are confidentiality, integrity and availability. Basic security terminology like identification, authentication, access control and confidentiality are explained. Common network vulnerabilities like weak passwords, protocol design flaws, and unauthorized access through modems are also discussed. The importance of network security is to protect company assets, gain competitive advantage and ensure regulatory compliance.