So, you’re on lemmy.world and I’m on lemmy.blahaj.zone. My login for Blahaj won’t work on lemmy.world, and yours for lemmy.world won’t work on Blahaj, because they’re two separate instances. An instance is a when someone has taken the freely available Lemmy software and hosts a site for others to join.

We can talk to each other because we’re both using Lemmy. We can also talk to people on Mastodon and few other sites that use the same method of sharing posts with each other (ActivityPub).

Different instances usually have different rules. What gets you banned on one instance may be fine on another; don’t worry too much about it and just choose a place you vibe with.