Final answer:
The /r parameter in the command shutdown /r /t 0 is used to restart the computer.
Step-by-step explanation:
The /r parameter in the command shutdown /r /t 0 is used to restart the computer. By including this parameter, the command will shut down the computer and then automatically restart it. This can be useful if there are pending software updates or if the computer needs to be rebooted for other reasons.