Rooting means installing a
su binary onto the device, which provides a way to become the
root (=Superuser, "su")
user on the Android system.
root has access to everything and thus you can do really nasty things with it.
If not already done, unlock your bootloader.
These apps are only for updating an already installed binary, so you'll need the installable zip file for your desired binary:
The stock recovery only allows flashing zip files from a special directory you can't access yet. So you'll need a custom recovery to work around this limitation.
There are - again - 2 options: ClockworkMod (CWM) Recovery or TeamWin Recovery Project (TWRP). I prefer the latter one.
- ClockworkMod Recovery (download "touch" or "non-touch" version)
- TeamWin Recovery Project (download the recovery image, not the app install method)
Step by Step