Think of it like your email provider: you can still get email from Hotmail even if you have an AOL.com account.

Where this analogy breaks down is that some instances have defederated from others. This means “we don’t want your data, and we won’t import it.”

But if you pick an instance that is widely federated then you can see and interact with most of Lemmy.

An instance is a server. You can always communicate with everyone on your own server. You can also communicate with everyone on any other server yours is connected to. Not every server is connected to every other; but most are connected to most.

You don’t need an account on each one, but you may want to set up a second account on an instance you like to use as a backup. I have accounts on midwest.social, slrpnk.net, and piefed.social; they all see the same content 99% of the time. But every so often midwest goes down for maintenance, or slrpnk has a firewall issue, and on those days I just switch accounts and keep going.

Imagine that all of the instances existed first - before federation even existed.

So imagine dozens of little, independent message boards - this person created one at this address, and this other person created this other one at this other address and so on.

Okay - then imagine that federation came along, so then all of those individual bosrds started sharing content with all the other boards.

So you were on this one board called lemmy.world. You never moved - you still have the same account at the same board. But now you also see, for instance, content from some other board called lemmy.ml.

Now here’s the important bit - you aren’t actually looking at lemmy.ml. You’re looking at a mirror of it - literally, you’re looking at lemmy.ml@lemmy.world. So like this community we’re on right now - neither one of us is actually on AskLemmy@lemmy.ml. You’re on AskLemmy@lemmy.ml@lemmy.world and I’m on AskLemmy@lemmy.ml@sopuli.xyz. But every few seconds, all three of those actually separate communities sync up with each other, so it acts as if it’s just one community.

Does that help?

I think of it like this

Let’s say 3 families each have a magic book they can use to communicate with each other. Anything someone writes in one book appears in all 3 books.

Each book is a Lemmy instance. In the real world it would be a server running the Lemmy software.

The family members are the users of each Lemmy instance.

And the spell that binds the books together is federation.

Now let’s say family 1 and 3 have a falling out and break the spell connecting their books. That’s defederation.

Everything they wrote in the books before then is still there. But nothing they write going forward will sync to each other’s book. They can both still see and write on family 2’s pages, but won’t be able to see what each other write. Family 2 can still see all of both of what of them are writing because he’s still federated with them both.

Now let’s add some of the other fediverse services into the mix. Lets say mastodon, it works pretty much the same way, but instead of a book, let’s say it’s more like a stack of index cards, but otherwise you can see whats in everyone else’s stack of cards as long as you’re federated with them.

Most of the fediverse services federate to some extent or another with the other services. It can be a bit weird sometimes, index cards of course wouldn’t have a page number in the book, and pages in the book wouldn’t be indexed in the card catalog, so searching out the content from those other services can be a little wonky, but if you know where to look you can find those cards tucked into your book, or a crumpled up page from a book tucked into your card catalog, and you can interact with them, so you’ll sometimes see, for example, someone from a mastodon instance commenting on a Lemmy post, which is kind of like taping one of their index cards to the page of your book to leave a comment.

An instance is like an island. Few instances have connections to every island out there, yours in particular has removed your ability to see anything posted on the communist instances. What you see on “Local” is what’s posted on Lemmy.world, what you see on “All” is every island your island is connected to.

The benefit of local searching is that some instances have themes, like Hexbear.net with communism/anarchism, Lemmygrad.ml with Marxism-Leninism, slrpnk.net with the solarpunk movement, or mander.xyz with science. You can scroll locally and see what you’re interested in, or you can go to all and see what other instances are saying, and participate in their communities.

Hello from Lemmy.ml!

We’re seeing each other’s content even though we’re using different websites and different apps. That’s the fediverse for ya!

Do I need a different account for each instance?
Not to post to an instance that federates with your home insurance. Like with this post, your home instance is .world and you posted to a community on .ml If you want your home instance to be .ml then, yes you would need an account there.

Not all instances communicate with one another. My home instance, Sopuli, does not communicate, or federate with nsfw instances, among others. If I wish to interact with those instances i need to create an account there, or on an instance that does communicate with them.

So imagine a whole bunch of walkie talkies connected together. Your instance is your brand of walkie talkie. You can still communicate with the other ones they’re just made by a different brand.

If you want you can personally filter out which brands of walkie talkies you can communicate with.

Other times your brand of walkie talkie might decide it doesn’t want anyone using its walkie talkies to communicate with another brand of walkie talkies. This is usually called defederation

In general if you stick to .world you’re mostly okay to not worry about it and you’ll have a good time. You might decide you don’t like .world because their defederalising from walkie talkie brands you want to talk to. In that case you can switch to a different brand. You’ll have to make a new account though. There are some account transfer tools but it’s still pretty new and not quite fleshed out.

It’s ok. I been here for months and have no idea how it works.

Your account is on lemmy.world. You can see the other instances that lemmy.world federates with and which ones it blocks by going to https://lemmy.world/instances. You will be able to see any content posted to lemmy.world as well as any instances in the “linked instances” list. You won’t be able to see content from the “blocked instances” list. Most instances get blocked for being the source of spam or trolls.

You’d only need to make an account on another instance if you want to participate in communities that are on instances that lemmy.world blocks.

I’m not calling you dumb, but you should interact more with people. 4h ago you made a post:

“Reddit employee” scared that people are gonna move to Lemmy soon.

But instead of ineracting with the comments you got - many of them partially explaining what you are now asking - you just make another lazy post. And you haven’t interact here with anyone either.

edit: lol, of course OP would reply now that I called them out.