What are the permission protection levels in Android?

There are three main permission protection levels in Android:

1. Normal permissions: These are permissions that have minimal risk to the user's privacy or the device's operation. They are automatically granted by the system at installation time and do not require explicit user approval. Examples include ACCESS_NETWORK_STATE, CHANGE_WIFI_STATE, INTERNET, SET_WALLPAPER, etc.[1][2]

2. Signature permissions: These permissions are granted by the system only if the requesting app is signed with the same certificate as the app that declared the permission. They are used for interactions between apps from the same vendor. Examples include BIND_ACCESSIBILITY_SERVICE, BIND_AUTOFILL_SERVICE, BIND_DEVICE_ADMIN, etc.[1][2]

3. Dangerous permissions: These are permissions that give the app access to the user's private data or control over the device that could potentially affect the user experience. Apps must explicitly request these permissions at runtime and the user can grant or deny them. ...