Defense in depth
DiD refers to a strategy that places multiple layers of different forms of defenses between attackers and the resources you are trying to protect.
Adopting a DiD strategy allows an organization to adopt a strong security posture and help ensure that all systems, data, and users are better protected from threats and compromise.
A DiD strategy means there is no single layer of protection or security service that is solely responsible for protecting resources, but by implementing many different types of defense at individual layers, you can slow down an attack path. It may successfully breach one defensive layer but be halted by subsequent protection layers, preventing the protected resource from being exposed.
The following screenshot shows that DiD as a concept is nothing new as a strategy; it can be considered the medieval castle concept of protecting resources:
The medieval castle...