Learn the Layered Security Model (Defense-in-Depth)

A single wall is easy to break through, but a fortress with a moat, high walls, and guards is much harder to conquer. This is the principle behind layered security, or "defense-in-depth." This article explains how cybersecurity professionals use multiple layers of defense—from physical security and network controls to application security and user education—to protect critical assets. This is one of the most important strategic concepts in all of cybersecurity. It explains how all the different subdomains you've learned about work together to form a cohesive defense. Understanding this model allows you to think like a security architect, designing systems where if one control fails, another is there to stop the attacker.