Sure! So, you cannot log in to any server using the same identity. For better and for worse, your identity is attached to a server (or more accurately, a server is attached to your identity) so your login will only work with one server. As far as how we can both see each other’s stuff, that answer likes within the ActivityPub specification. I haven’t read fully into the spec, but the executive summary is that your server just displays information it has cached, and that other servers send it information to cache.

When you look at any feed, comment section, or thread, you are looking at an aggregated presentation of content from many servers that your server sends and receives messages to. As such, your feed is a reflection of both the content you have expressed an interest in by subscribing to it or clicking into it, but also the moderation style of the admin of the instance attached to your identity. As such, it is important to distinguish that it is factually inaccurate to say that which server you join when you sign up doesn’t matter.

Finding a server that is run the way you would want a server to be run will not be an instant process. The first step is to read the documents that an instance you’ve found has socialized. Do the rules sound good? The second step is to look at the local feed on that instance. Are you interested in the posts? Do any of them raise red flags? The third step is to sign up for the instance and try it out. Does it feel good to be there?

Obviously, since we’re already having this conversation, you’ve signed up for lemmy.ml. No matter how rigorous your vetting process, you still did enough to say you were interested in what was going on there, even if you didn’t fully understand it. Imagine if someone’s first impression of Lemmy was slrpnk.net. It would look like there isn’t that much activity, and all of it is about ecology and climate change. Meanwhile, you went to lemmy.ml and didn’t notice anything off. Done. That was a step.

So now. That final step after you’ve signed up for an instance where you decide if you’re going to stick around. This is where you pay attention to if there are consistent moderation issues with the instance you are on. To describe my personal experience, slrpnk.net is the third instance I’ve signed up for. The first instance I signed up for was on beehaw.org, and that remains my primary account. But about 3 weeks ago, Beehaw decided to defederate from a pair of large instances because they didn’t have the capacity to moderate the onslaught of content coming from those instances. I was subscribed to a few communities on those instances. I had been enjoying content coming from them. Most of the users weren’t problematic. So, I figured I’d set up a secondary account on another instance to view the content I was missing out on. I would just do my own blocking of content I would rather not see, since Lemmy and KBin provide better blocking tools than Reddit ever did.

That secondary account quickly ran into problems as the moderators from that instance let too much slide, by far. This is where the other part of deciding if you want to stay on an instance comes into play. I noticed in my time on that secondary instance a pattern of liking what people from slrpnk.net had to say about things (as well as disliking what people from exploding-heads had to say). I decided I wanted to be on an instance where I wasn’t constantly blocking content from one instance because it was already defederated. When I saw slrpnk.net was in fact defederated from exploding-heads, I knew it was a good landing place since I already felt a spirit of agreement with their userbase, so I joined.

I hope that clears things up. As much as possible, I want to reduce how intimidating all of this can seem. I’ve been interested in the fediverse for a long time. It’s only recently really gotten a way to interact with it that both has enough people on it to seem worthwhile AND matches the ways I like interacting with the internet (on forums). I realize it can look a little odd for someone with young accounts (@Cube6392@beehaw.org, @Quill7513@slrpnk.net , and @Quill7513@sh.itjust.works are all me) to speak at length about these topics. I first signed up for a mastodon instance in 2016, and I had many of the same questions and confusion you did. I want to give people a more comfortable on ramp than I had.

Does all of that help?