Life After Facebook: what is this "Fediverse" thing anyway?
... and why should I care?
(Feedback on whether this is a reasonable explanation is welcome, too.)
Facebook sucks, but it's the only thing out there, right?
Well, actually, there are alternatives. I don't know of anything that's exactly Facebook-like, but if you're looking for the pattern of "you post stuff / share links / pictures and others can comment / reply / reshare", there is e.g. Mastodon (... kinda like Twitter), Pixelfed (... kinda like Instagram), PeerTube (... kinda like YouTube), etc.
... and why is this different, exactly?
Of course, "traditional" social media (FB, Twitter etc.) is not that great because it's them who decide what you get to see (while they track you in the process & sell your data / eyeballs). So... why is e.g. "Mastodon" better? Aren't they going to sell all your data, too?
They aren't really going to, since there is no "they". It's not one thing, it's a piece of software that multiple providers can run; the good thing is that these can still talk to each other.
It's a bit like signing up with a mobile carrier: they give you a phone number, but you can still call your friends on other carriers. You don't have to have three separate phones, one for T-Mobile, one for Verizon etc.
For example, there is a Mastodon instance called Fosstodon, run by a couple of cool people, generally collecting people who are interested in Free and Open Source software. You can sign up and have a profile (e.g. here is mine), just like on Facebook / Twitter. You can follow people on Fosstodon (just like with Twitter). You can, however, also follow users on e.g. mastodon.social, which is another Mastodon instance, run by a whole different set of people, independently from Fosstodon. They don't even have to be Mastodon users: it also works with people on e.g. Pixelfed instances; if they post something, it'll show up on your timeline once you log into Fosstodon / your home instance.
And this is better... how?
Facebook can track you and push ads on you because, in order to see what your friends are posting, you need to log into Facebook. Their website, their rules. They have thousands of engineers working on how to sell your eyeballs the most efficient way.
They can do this because, obviously, everyone wants to be on the social network site where everyone else already is. No one would care about an alternative, smaller site that is much better but none of your friends are on it.
Now, imagine if you didn't have to be on the same site to interact with them? Just like you can exchange emails with someone using Gmail even if you aren't using Gmail yourself?
This way, it's viable for just a couple people to run a site, with only dozens or hundreds of people on it, without having to make a profit or do shady things. So this is exactly what's happening. No ads (because if your instance starts pushing ads & you don't like them, you just move to another one), and no algorithmic manipulation either (... for the same reasons).
So how do I sign up?
You pick an instance. Admittedly, there are a lot of people interested in "free software" or software in general; if you're one of them, I can definitely recommend Fosstodon: everyone is cool and friendly and there is a lot of interesting things going on on the local timeline. (Yes I didn't quite expand on what that is...) If not: ... probably this is one of the big unsolved questions of the Fediverse: how do you pick a good server?
... but then you can always move later!