What is an instance?
Some don’t like this comparison, but effectively think of lemmy in similar forms to e-mail, IE you can e-mail your friend who uses a different mail service, by adding @whatever.com to their username. the whatever.com in e-mail that’s called a domain usually, but in lemmy that’s considered the “instance”. The only difference is rather than just saying “that’s not an address” lemmy assumes if you don’t specify, you must mean the one where you are.
marighost@piefed.social 2 days ago
Your instance is the web domain that is hosting Lemmy. So, the instance you joined is lemmy.world. There are many instances, like lemmy.world, such as lemmy.zip, lemmy.today, lemmy.ca, and lemmy.ml (just to name a few). Additionally, there’s Piefed, and there are Piefed instances like Piefed.social (where I reside), piefed.world, etc. These instances all share content via “federation”.
When you’re logged into lemmy.world, you can use the built in search features to find communities (subreddits) you want to subscribe to, to see content posted there on your home feed.