Defense in Depth

A security approach that uses multiple layers of defense so that if one layer fails, others still stand. Instead of relying on a single barrier, you deploy a series of safeguards - overlapping layers - to protect assets. For example, to protect important data you might combine network firewalls, endpoint antivirus, encryption, and regular backups.

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If a phishing email gets past your spam filter (first layer), a well-trained user might still spot and avoid it (second layer), and even if they click it, your endpoint antivirus might block the malware (third layer).

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Defense in depth acknowledges that no single control is foolproof, so it builds resilience by having redundant protections. This strategy is especially useful for SMBs: even simple layers (like a secure router + antivirus + cloud backups) can significantly raise your security level when combined.