It’s good practice to backup your configuration to a TFTP server
so you should copy your config either your running config
or startup config to a TFTP server
so that you have a backup stored somewhere else.
This would be useful for example if your router failed
and you have to replace the device with another router
you could simply copy the config from the TFTP server back to the router.
So either to the startup config which is a replacement
or to the running config, which is once again a merge of configurations.