There’s two ways to root your Samsung Galaxy Note 4.
If you are going to be installing custom ROMs, see How to Root Galaxy Note 4 using CWM/TWRP Method. (You can get OTA updates by installing stock rooted ROMs when OTA updates are out. This will allow you to keep root and get OTA updates.)
If you just need to root and you also want to take OTA updates (as installing CWM/TWRP recovery will disable OTA updates), see How to Root Galaxy Note 4.
Need to unroot? Stuck on bootloop? See How to Unroot Galaxy Note 4 with Stock Firmware!
How to Install Custom ROM on Galaxy Note 4?
First, make a backup ROM before installing a custom ROM on your Note 4. See How to Backup/Restore ROM using TWRP Recovery!
Never installed a custom ROM? See How to Install Custom ROM using TWRP!
How to get OTA updates after rooting?
We recommend you install rooted stock ROMs instead (so you don’t have to re-root) but if you want to take OTA, you can re-install stock recovery.