An authorization layer is the runtime control point that decides whether a requested action should be allowed. It sits between an identity and the systems it wants to reach, checking permissions before an API call, file change, workflow step, or other operation is executed. In practice, it turns policy into a live gate: the request is either approved, denied, or constrained based on rules such as role, scope, risk level, or context.
This matters because cyber attacks often succeed by abusing legitimate access rather than breaking in directly. If an agent, user, or service is tricked into asking for too much, the authorization layer can stop the action before damage occurs. Defenders use it to enforce least privilege, separate read and write access, and log suspicious behavior for review. In agentic AI systems, it is especially important because prompt injection or over-privileged tools can push an agent toward unsafe real-world actions.