Instead of 1 big website like reddit, there's a bunch of smaller websites like reddit. These sites are united in a way as users from one site can view, comment on, etc on other sites.

Something similar is Email. Even if you made your email address with Google to have @gmail.com at the end of your email address you can still send and receive emails from anyone.

[–] [email protected] 1 points 1 hour ago

Unless your community or community owner pisses off all the other communities or just community leaders.

[–] [email protected] 8 points 8 hours ago

Welcome to Lemmy, here are a few pointers to help you settle in

[–] [email protected] 15 points 11 hours ago

It's pretty close to Reddit, but it's like a whole bunch of smaller Reddits that share posts between each other. The individual Reddits (instances) are generally grouped by hobby, political affiliation, or geographical location, but not always.

You can tell what instance something or someone is from by looking at their name or title. E.g. I'm from lemmy.zip, you can see it after my user name.

The reason that it can't be bought by a billionaire is that even if one instance is bought out, compromised etc, it can just be removed from the group at large, and it continues like nothing happened. I'm simplifying a bit but I hope you get the general idea.