This document discusses security issues in information technology. It defines information security as protecting information and information systems from unauthorized access, use, disclosure, disruption, modification or destruction in order to provide confidentiality, integrity and availability. The document outlines some key security issues like malware, viruses, worms, phishing and ransomware. It also discusses some common security measures used in IT systems like firewalls, encryption, anti-virus software, backups and continuous updates.