Why good security always has a backup plan for its backup plan

Wed, 26 Aug 2026 11:30:45 +0900

🤔 What Is It?

defense in depth

Defense in depth means protecting your stuff with many layers of security, so even if a hacker breaks through one layer, several more layers are waiting to stop them.

🧩 Like defending a castle

Imagine a medieval castle. To reach the king’s treasure room, an attacker would first have to swim across the moat, then scale the high outer wall, then get past armed guards at every inner gate, then pick the lock on the treasury door, and finally crack open a heavy iron chest — all without being spotted by lookouts on the towers. No single wall keeps the castle safe; it is the combination of every obstacle working together. If the moat gets bridged, the outer wall is still standing. If someone sneaks over the wall, the guards are still there. Defense in depth works exactly the same way for computer systems.

Security-Layers on Explain It

Why good security always has a backup plan for its backup plan

🤔 What Is It?

🧩 Like defending a castle