There is no ‘main’ website. It’s all connected. People just started joining that because it’s big and overloaded it, and now it’s having federation and stability issues.
I am new here so sorry for asking this, but am I expected to join the same communities on 75 different Lemmy clones?
Federation means you can search for your community on your instance and it will fetch all the information if you want to subscribe. I am writing this comment with my account on feddit.de. I just switched to the „all“ feed, which shows all content from all servers feddit federated with. If I am looking up a new community to join like communityname@servername.tdl feddit will copy the posts for mento be able to interact with them. My reactions will be synched back.
