A community is just that, a community. It's analogous to a subreddit, if you're familiar with reddit. One can start a community by clicking "Create Community" at the top of the Lemmy webpage on your instance. This community will be hosted on your instance, say you create a community for dogs, the community would be !dogs@lemmy.fmhy.ml.

Your instance can be compared to a email provider. The instance is hosted on a server, as in you connect to a server which has set up the Lemmy software, which connects to the ActivityPub protocol. The ActivityPub protocol is what enables kbin or Mastodon users to interact with communities here.

Compare this to email, where an email provider (say Gmail) is hosted on a server, which you connect to. If done via a web browser, the server will direct you to their web app (the interface you use on gmail.com) which connects to the SMTP (which is the protocol that handles email).

Just like how I can receive your email sent from Gmail on my Yahoo account, we can interact in communities together despite having signed up on different instances.

[–] Reed@lemmy.world 1 points 1 year ago

Instance and server are interchangeable. Instances have multiple communities, as many as you want. Beehaw instance only has like 20 while Lemmy.world has hundreds. Starting a community on an existing server is filling out a form, basically signing up for a website. Starting an instance requires hardware, metal or cloud, some experience with server software and command line interfaces, and patience. Any Lemmy server can federate with all other servers so you can show up on my feed when I hit "all" instead of "local." You can be defederated with for technically any reason by any server. It doesn't happen often outside of beehaw and most of their defederation list is like Neo Nazi shit.