crt.sh is a widely used tool in security research and OSINT that provides visibility into SSL/TLS certificates published through Certificate Transparency logs. By working with publicly issued certificates, it helps uncover subdomains, map hidden infrastructure, and monitor certificate activity across domains.

Its simple interface hides a powerful data source that can reveal forgotten services, internal environments, and unexpected relationships between domains.

Authentication and authorization are two core security processes that work together to protect systems and data. Authentication focuses on verifying a user's identity, while authorization defines what resources and actions that user is allowed to access. Understanding this distinction is crucial for building strong security.

A useful analogy is an airport: first, a passenger's identity is confirmed, and only then are their privileges determined – such as boarding class or lounge access. In digital systems the logic is the same. Authentication ensures users are genuine, and authorization grants specific permissions based on roles and policies. Proper configuration of both mechanisms is essential for any secure environment.