TFTP: Trivial FTP
It doesn't use user authentication, and other things...
Usually it's used to make remote boots, in diskless PCs. To download the file that boots the machine.
Or to restore PCs from fresh image disks (automatic installations)
I think you know well the use of the usual FTP.
To enable TFTP, you should install the package. Edit the tftp file in the /etc/xinetd.d/ ,configure it correctly and restart the xinetd service "service xinetd restart"
Good luck!