What IS "nudism"

There are a lot of topics that come up frequently on this site. There are a few that come under the category of "frequently asked questions" which get asked repeatedly by those new to nudism or to this site about "nudism" and nudist activities. Sill there are others that even established nudists bring up for discussion on this site. Some may get discussed for a period of time and then go away. Others are immediately met with opposition. And the discussion centers not around the topic but whether or not the topic has to do with "nudism".

So what IS "nudism"?

Depending on the society you're living in or frequent, there are simply some topics that aren't discussed in public or that people aren't comfortable discussing. This has nothing to do with whether people are naked while involved them or they're clothes or start of clothed and eventually get naked. But does the comfort levels of individuals or the society they live in dictate what is or isn't "nudism"?

And if there are societal "norms" for nudists that somehow differ from textiles in defining what "nudism" is, then who gets to decide what they are? And who gave them the authority to do so for that matter?