So a bunch of these federated sites (instances) use the same protocol (ActivityPub) therefore they can talk to each other. Kind of like email can talk to other email servers using the same protocols (e.g. SMTP).
Mastodon (Twitter Clone) is the largest off all the federated social media software.
Lemmy (Reddit Clone) federates with other Lemmy instances + Kbin instances.
Kbin (Reddit + Twitter Clone) can talk to Lemmy instances via Magazines/Threads and Mastodon instances via Microblogs.
https://kbin.social/m/mcmansionhell@sh.itjust.works
This should work after searching the URL straight from kbin… but searching it right now gives me a 500 Server error. Seems like it’s having technical issues.