Fediverse

The thing that I love about it is that you can host your own account. So if Bluesky decides that they are huge fans of fascism, you can take your account and move to a competitor, Redsky, and not lose your posts, messages, follows, etc (assuming those people also move to the new platform)

So, your account can be the same between any number of platforms, you just have to let the platform add it to their list so their crawlers can show your activity.

And, like Lemmy, you can host your own "node" (I forget what they call it. A box that can whitelist, crawl, and display accounts that people want to be visible there, similar to an instance) but you can also just host your "account" and you can bring it to whatever platform you want and people can be confident they've found the same person.

Projects like https://a.roomy.space/ are also super interesting. It's sort of like how Lemmy uses and reformats the content you might see on Mastodon into a traditional forum, except Roomy can use the AT Protocol to format it into a sort of Discord concept. It's public, but they also are working on private, self-hosted 'rooms' as well. There are also other projects that reportedly have managed E2E encryption for private messaging. (Edit: on this topic, ATP is very pointed at public content. Any encrypted messaging solution isn't likely using ATP for the messaging, just for your web identity. The major thing here is having a consistent presence and login that you and your friends can follow to various platforms without issue and can't be controlled by another entity).

I'm super not a technical nerd, so I'd have to go reread documents to give you any specifics about it as a whole. And even then, I can only really understand them to the extent that I'm not actually a developer on the protocol, so I don't have a first-hand understanding of how it works, but the concept of it and what it seems to enable is just really exciting to me.