What is defense-in-depth?

Defense-in-depth is a cybersecurity strategy that employs multiple layers of security controls to protect an information system. The strategy aims to provide redundancy in case one security control fails or is bypassed. It commonly involves using a combination of physical, technical, and administrative security measures, such as firewalls, intrusion detection systems, access controls, security awareness training, and physical barriers, to create a layered defense against potential threats.