Per-app permissions are access controls that apply to one program at a time instead of granting the same access to every app on the system. For example, a desktop program may be allowed to use the microphone while a call is active, but blocked from using it at other times or from accessing the camera and location data at all.
This matters because cyber security is often about limiting blast radius. If an app is compromised, or if it quietly expands its behavior through an update, narrow permissions can reduce what an attacker can reach. Per-app controls support least privilege by making it easier to revoke unnecessary access without disabling a sensor or service for everyone. In real defenses, they help users and administrators audit which applications can touch sensitive resources and remove permissions that are no longer justified.