all good dude, it’s easy to get that confused. lemmy.ml is actually just one of a number of websites that make up lemmy and the fediverse at large. while you interact as a user almost exclusively through your home instance, much of the content you can access is actually hosted on a different website, even though you still access it through your home instance, think if it like email in that sense. even if you don’t have a gmail.com email address you can stil send and receive emails to people who do. that’s why my full handle is @this@sh.itjust.works, yours is @Marv@lemmy.ml, and we are communicating with each other on a public form via the individual websites our accounts are hosted on. If you have ever used or plan to use mastodon, that works the same way and actually uses the same protocol (activitypub), there are also other currently less popular social media alternatives that use this protocol as well as speculation that it may be added into some mainstream social media platforms(though I wouldn’t hold my breath on them federating with lemmy/mastodon). If you ever join a smaller instance (which I and the devs recommend to help the network scale better), you can use this link to find communities on other instances(they won’t show up on your home instance if no one is subscribed to them or they are blocked by your instance): https://browse.feddit.de/