@Benjamin its basically automatic e-mail in the sense that it doesn't matter what e-mail provider you're on but you can still contact each other across mail providers
Here you can substitute mail providers with social media platforms, and it happens ✨automagically✨, without anyone doing anything
To put this into perspective, I see hundreds of posts that aren't by people that signed up on wetdry.world on my home feed, and I can still interact with them, yet wetdry.world is my home.
Maybe the little explanation video on https://fediverse.info helps
@big_slap
Fun fact:
The entirety of bluesky was supposed to be an activity pub extension at some point.
https://gitlab.com/-/snippets/2535398