When you see “offline” for a device in the Find My iPhone feature, it means that the device is currently not connected to the internet. This can occur for several reasons:
Turned Off: The iPhone or iPad may be powered off, either because the user turned it off or the battery has died.
No Internet Connection: The device may be turned on but is not connected to Wi-Fi or cellular data. This can happen if the device is in airplane mode or if it is in an area with no network coverage.
Location Services Disabled: If the device has location services turned off, it might not be able to send its location to iCloud, resulting in it being listed as offline.
Signed Out of iCloud: If the user has signed out of their iCloud account on the device, it will be unable to communicate with Find My iPhone.
Factory Reset: If the device has been reset to factory settings, it will no longer be associated with your Apple ID and will not show up in Find My iPhone.
When a device is offline, you can still perform certain actions, such as marking it as lost or enabling notifications for when it comes back online. However, you won’t be able to see its current location or perform actions that require a live connection until the device is back online.