'adb devices' is not listing my phone I am trying to do a full backup of my Galaxy Note 4.1.2 phone using the adb command. t says it couldn't connect to my device. Then I did a 'adb devices' and there where no listed devices. My Windows File Explorer shows my phone and I can browse its contents.

Any ideas why the device can't be listed?
The fact that you see the device from your File Explorer doesn't mean that is should work from ADB. Most phone support standard file transfer protocols such as MTP and/or mass storage.

To use ADB you need to install the USB driver that is associated to your device. For Samsung devices you can search for downloads related to your particular device but I guess installing Kies would also do it. Then you need to enable USB debugging from the parameters -> development screen.

After this is done you should see you device when running adb devices.