Sensor access is permission for a program to use hardware sensors such as a camera, microphone, GPS receiver, or other location-capable device. Operating systems usually gate this access behind prompts or settings so users can allow or deny it, and in some cases restrict it to a specific app.
This matters because sensors expose highly sensitive data about what a person sees, hears, and where they are. In attacks, unwanted sensor access can support surveillance, voice capture, or location tracking if malware or over-privileged software abuses those permissions. In defense, app-level controls and revocation support least privilege: an app gets only the sensor access it needs, for as long as it needs it. That reduces the impact of buggy software, abuse by trusted apps, and permission sprawl across a system.