Secure-by-Design is a development approach that embeds security controls, threat modeling, and safe defaults into a product from the earliest design stages. Instead of treating security as a final review, teams plan for authentication, authorization, input validation, logging, update mechanisms, and least privilege before code is shipped.
This matters because many attacks exploit design weaknesses, not just bugs. Weak identity flows, exposed admin interfaces, insecure APIs, and poor data handling are easier to abuse when security is added late. In practice, secure-by-design shows up in code review, architecture review, secure configuration baselines, and continuous testing. Defenders use it to reduce the attack surface and make compromise harder even when an adversary gains access. In governance terms, it turns security into a product requirement, not a patching exercise.