What is federation, and why?

I made a video explaining ourch.at if you hate reading, which you can watch above! 
 Why the web sucks now 
 The original vision of the web was an open protocol that anyone could build on. Then, people became billionaires by creating their own walled gardens inside the open ecosystem of the web, and called them "platforms." 
 If you want to see instagram posts, you need to use instagram. 
 If a shitty billionaire buys the platform you use and enshittifies it, you can't take your followers elsewhere. They're locked into that platform, and so are you. This is not good, and it's no longer viable now that the attention economy is making us so unhappy. 
 Federation as a solution 
 Federation is the idea that we should have social media that is decentralized in the same way that email is decentralized. Nobody owns email. If I have an email address ending in @gmail.com, that doesn't prohibit me from emailing people with an address ending in @yahoo.com or @hotmail.com or any other domain. It's an open, interoperable protocol that we all use all the time! 
 So if email is the protocol, what's the social media protocol? It's an open standard called ActivityPub . You even get an address kind of like with email! 
 My social media address is @rob@mic.ourch.at My audio address is @rob@aud.ourch.at My messaging address is @rob@m.ourch.at 
 How do these work in practice, though? I'll use my server, ourch.at, as an example. 
 mic.ourch.at (twitter-like) 
 This website runs an app called "Mastodon", which is a microblogging platform kind of like Twitter or Threads. There are tons of apps that implement the ActivityPub protocol, and Mastodon is just one of them! I chose it because it's the most popular and feature-complete ActivityPub-based social media app so far. 
 You're not limited to following and interacting with other people who use servers running Mastodon, though!! Any server running an app that uses the ActivityPub protocol can talk to any other server running an app that uses the ActivityPub protocol, regardless of the app. 
 aud.ourch.at (spotify-like) 
 This website runs an app called FunkWhale that basically acts as a music server for hosting your audio files, which is great for streaming from your phone and other computers! I like to connect to aud.ourch.at using the Amperfy app, which has a way better user experience. 
 msg.ourch.at (discord-like) 
 This one works just a little differently! Your address will use the format yourname@m.ourch.at, because that's where the "Matrix" messaging server is installed. However, m.ourch.at doesn't actually have any front-end interface at all! For that, you can go to msg.ourch.at, which runs a front-end called Element to facilitate the messaging. Technically, though, you could send messages through your @m.ourch.at email address using whatever matrix-enabled app you want.