Defence in depth

Ok kiddo, so imagine you have a really important treasure that you need to keep safe. You wouldn't just put it in one spot and hope nothing bad happens, right? No, you would want to have lots of different ways to protect it.

That's kind of like what defence in depth means when it comes to keeping important things like computer systems safe. Instead of just having one security measure - like a password - we have lots of different layers of security that work together to keep stuff safe.

So first, there might be a firewall. This is like a big bubble around all the important stuff that only lets certain things in and out. Then there might be antivirus software that scans for any bad stuff trying to sneak through the firewall. And there might be even more layers of security beyond that, like different passwords for different parts of the system.

This might seem like overkill, but remember - just like how you would do everything you could to keep your treasure safe, people who make computer systems have to do everything they can to keep important information from being stolen or attacked. So by using lots of different security measures that all work together, they can make sure that even if one layer fails, the treasure is still protected by other layers. So that's what defence in depth means - lots of different layers of security working together to keep important things safe.