Whitelisting
Whitelisting is a security and access control concept where only explicitly approved items (such as applications, IP addresses, or users) are allowed to operate or access a system, while all others are denied by default. It is commonly used in cybersecurity, network administration, and software deployment to enforce strict policies and reduce the attack surface. This approach contrasts with blacklisting, which blocks known threats while allowing everything else.
Developers should learn and implement whitelisting in scenarios requiring high security, such as in production environments, compliance-driven applications (e.g., healthcare or finance), or when deploying software in controlled systems like kiosks or IoT devices. It helps prevent unauthorized code execution, mitigates zero-day attacks, and ensures only trusted components are active, making it essential for roles in DevOps, security engineering, or system administration.