I’m still trying to wrap my head around the whole federation thing. I got my account created on lemmy.ml, but I see that I can set the front page include posts from the whole federation, be it beehaw, etc.

Now I’m confused about actually posting stuff. For example, on the lemmy.ml frontpage sidebar, there’s a rule 3, no porn. Is it instance-wide? Or is it just for /c/lemmy community? Can I create my own community with nsfw comment? And if not, can I use a federation to post a nsfw content to an instance that allows nsfw from my account on lemmy.ml?

There’s a docs page here: https://join-lemmy.org/docs/en/users/01-getting-started.html, but I feel there needs to be more comprehensive and idiot-friendly ELI5 version of federartion and how is it actually impleemented, because its such a huge paradigm shift which most of people are not used to.

EDIT: Also, can I create communities cross-instance for example?