If you are planning on rooting, installing custom ROMS, or backing up/restoring your current ROM on your Galaxy S4 you will need to download a ClockworkMod Recovery.
ONLY download the correct recovery for your SPECIFIC model number!!
ClockworkMod Recovery:
Download GT-i9505 Quad-Core Galaxy S4 ClockworkMod Recovery
Download GT-i9500 Octa-Core Galaxy S4 ClockworkMod Recovery
Download SGH-M919 T-Mobile Galaxy S4 ClockworkMod Recovery
Download SPH-L720 Sprint Galaxy S4 ClockworkMod Recovery
Download SGH-i337M Canadian Galaxy S4 ClockworkMod Recovery
Tools:
Odin
USB Drivers