Defense in depth is a cybersecurity approach that involves building multiple layers of security measures to prevent attacks, rather than relying on a single layer of protection. This approach assumes that attackers will eventually breach any given defense and requires companies to prepare for such an eventuality by adding additional layers of protection. The defense in depth strategy consists of three main layers: physical, administrative, and technical controls, which work together to create a robust security posture. By adopting this approach, companies can make it more difficult for attackers to succeed and reduce the risk of data breaches. Defense in depth is particularly relevant in today's highly networked environments, where attacks are becoming increasingly sophisticated and scalable.