There’s a protocol for federating social content over the web. It’s called ActivityPub, based on ActivityStreams 2 vocabulary. Recently, it was accepted a standard at W3C (that’s the guys who basically run the web, so some protocol being a standard is a pretty big deal)
To the full extent, it is described at W3C’s own home here: https://www.w3.org/TR/activitypub/ but that’s not all that human-readable as standards are, you know.
So, here’s rundown on how to implement basic stuff the ActivityPub has to offer, by Mastodon creator:
So, once you put those things in place, you then will be able to:
a) federate Ghost with other Ghost instances (which is, you know, a perk)
b) federate with Mastodon, Pleroma, PeerTube, Plume, Hubzilla, Misskey, PixelFed, etc., because they implement the same ActivityPub protocol. They will see your posts in their feed as if you were in the same social network. That means a Mastodon user will reply to your article as if it was a Mastodon post, so will a Pleroma user, so will Misskey user.
I hope this helped to understand it better.