@Minotaur@henfredemars@technology You are using an account on lemm.ee to reply to someone commenting from an account on infosec.pub in a community hosted on lemmy.world.
Those are all running Lemmy software, but I am replying from an account on social.goodanser.com, which is running Mastodon software.
That's federation. We're all using different service providers, sometimes even different software, but we can talk to each other because they speak the same protocol, called ActivityPub. Threads.net has announced plans to support ActivityPub and conducted some limited trials, which they're in the process of expanding. They claim they intend to support it fully, but only for users who opt in to it.
Servers can block, or "defederate from" other servers, and many have chosen to preemptively defederate from Threads.