Root is needed if you want to Flash Custom ROMs and kernels.You can root Samsung galaxy j2, tweak your phone,overclock the CPU and use rooted application after rooting your device.
Remember rooting android device may void your warranty.(Credit-Chainfire)
How to Root Samsung Galaxy J2 SM-
J200H with SuperSU
- Download SuperSu Zip
- Place the SuperSu zip file to the internal memory of your Galaxy J2
- Now Boot your device into recovery mode(press and hold Volume Down button +press Power button).
- Choose install, and then select the SuperSU Zip file
- Tap on Reboot system