The most intuitive analogy to federation to me is email. You may have an account with one provider (gmail.com in the example of email, or lemmy.world in the example of Lemmy) but you can send emails to other providers (email example) or post messages to other instances (Lemmy).
Just like with email providers, a Lemmy instance may decide not to allow communication with another instance - this is “defederation.” Instances that allow communication are “federated.”
Just like email, you don’t normally need to worry much about whether you are on the same instance as a particular community or user - it just works.
This is a simplification, but for me is a good working model.
The most intuitive analogy to federation to me is email. You may have an account with one provider (gmail.com in the example of email, or lemmy.world in the example of Lemmy) but you can send emails to other providers (email example) or post messages to other instances (Lemmy).
Just like with email providers, a Lemmy instance may decide not to allow communication with another instance - this is “defederation.” Instances that allow communication are “federated.”
Just like email, you don’t normally need to worry much about whether you are on the same instance as a particular community or user - it just works.
This is a simplification, but for me is a good working model.