Hard soldering, silver soldering, and brazing all refer to soldering where the filler melts at over 420C…. Not sure what soddering is… :-) ...

Not hypothetical, I’ve soldered with a pipe fitting solder gun and giant solder; something like 3/16th inch flux core. Nasty flux, too, meant for pipes and not circuits.

It describes the conditions under which soft and hard soldering can be carried out most successfully, the best fluxes to use, and the proper way to apply them and the solder.