Foundations: The CIA Triad and Early Threats

Cybersecurity is commonly defined through the "CIA triad": confidentiality, integrity, and availability. Confidentiality means ensuring that information is accessible only to those authorized to see it, typically enforced through encryption and access controls. Integrity means guaranteeing that data remains accurate and has not been altered by unauthorized parties, whether through malicious tampering or accidental corruption. Availability means ensuring that systems and data are accessible to legitimate users when needed, which is why attacks that disrupt service, such as denial-of-service attacks, are considered a direct threat to this pillar. The model, refined through work such as the 1975 paper "The Protection of Information in Computer Systems" by Jerome Saltzer and Michael Schroeder, remains the conceptual backbone of nearly every modern security framework.