TWRP is custom recovery/backup is used for installing custom software on your device. https://twrp.me/devices/samsunggalaxynote3tmobile.html adb/fastboot are part of the free dev tools for android [win/mac/Linux bins] at google. XDA is a web-forum smartphone hacks info: page for note3: https://forum.xda-developers.com/galaxy-note-3