p.s. There's a short animation video by @Framasoft called "What is the Fediverse?"
https://fedi.video/w/9dRFC6Ya11NCVeYKn8ZhiD
TL:DW - The Fediverse allows people on independent social networks to follow and interact with each other without having to get an account on each service. This already happens on email networks and phone networks, why not social networks too?