No, you just need to go to that community while logged in with your lemmyworld account. Usually the url will become like this: http:// lemmy[dot]world/c/community@some.instance, and once you open that, you can post normally.

You do not need to create an account on that node as long as they are federated. I am on mander.xyz but I can post to lemmy.world and I do not have an account on lemmy.world

To keep it simple, no, any lemmy account will work with any instance*

*As long as thag instance has not decided to de-federate(remove it’s links to another instance of lemmy) from the instance you made you account on. (Looking at you beehaw)

If you don’t want to think about it too much.

In reality, you don’t have to worry about what instance a community comes from. If you like the content, just subscribe.

But, if you want to understand a bit more, here’s a few things explained.

Here’s a break down of the menus:

• Subscribed: posts from communities you subscribe to, from your instance and other instances

• Local: posts from the instance you signed up on

• All: posts from all instances (that allow connections from your instance)

If a community is on your instance it will just be the name (ex: cats)

If it’s from another instance it will have the @ with the instance name (ex: cats@lemmy.ml)

How does lemmy work?

• Unlike reddit or other social media, lemmy is not hosted on one server, but serval smaller servers running on the backbone of the same software.

• Each server is called an instance (examples: lemmy.world, lemmy.ml, lemmynsfw.com)

Think of it like forums back in the day, but a little different:

• You can have forums that are general, and you can have forums that are more focused on a single topic or group of things.

• just like these old forums, there are a few different general instances of lemmy, and also some more focused instances.

• in these old forums, there could be threads with overlapping topics in several forums.

• just like these forums, there can be overlapping communities in lemmy instances.

How is lemmy different from these old forums?

• these old forums were almost all completely self contained, if you wanted to interact with another forum, you needed another account.

• lemmy, on the other hand is federated meaning all if it’s instances are connected.

• Users can create one user account on just about any instances and that identity can be recognized on any instance.

• This also means users can follow any of the communities from other instances as well.

What is federation?

Federation is a complicated thing, and has many uses and implementations, but if you’d like to know more about Lemmy’s federation you can check out it’s documentation on that here:

https://join-lemmy.org/docs/en/administration/federation_getting_started.html#:~:text=Lemmy uses the ActivityPub protocol,yandex.ru and so on.