This page intends to inform the non-technical individual about what federation is, and why federated/decentralized services might be preferable to single-vendor/centralized ones.
The reader likely has used email to communicate. I personally have used a university GMail account, and there are others I know that have used an AOL or Yahoo email accounts. The beauty of email is that I can send a message to any email account, even if that account and my account are owned by different companies. The technical details of how email works were strictly determined and made public (i.e. they were standardized) so that anyone who wants to make email software can follow the standardized rules precisely, and thus be able to communicate with the email software run by Yahoo, Google, Microsoft, or anyone else (which of course follows the same, precise rules).
Email is the perfect example of a “federated” service; a federated service is one which allows many different providers of a service to communicate and collectively provide a unified experience of that service. We see this in email by the fact that I will “send you an email”, but I will not “send you a Yahoo email” or “send you a gmail message”. GMail, Outlook, and Yahoo work together to provide a good email service. An example of a non-federated service is Facebook Messenger. Although anyone with a Facebook account can send a message to any other Facebook account, they cannot send a message to an Instagram or Snapchat account. Of course, one cannot send an email to these services either, so this does not prove Facebook is not federated. The reason Facebook is not federated is that no one else can run software to provide the same services that Facebook provides. Facebook has not explained to society how their software works, so we can hardly hope for anyone else to provide a compatible service.
Email is not the only federated service. For texting, instant messaging, and chatting, Matrix and XMPP/Jabber are both good options for replacing Facebook Messenger, iMessage, or regular SMS texts from your phone plan. For social media, the Fediverse is a collection services that replace common non-federated ones; Peertube replaces YouTube, Mastodon replaces Twitter, PixelFed (not yet finished) replaces Instagram, Plume replaces Medium, and there are others as well.
There are two benefits to using federated services (there are more reasons, but I’ll only list two); the first is technical, the second is safety related. The technical reason is that if one provider of a service gets shutdown, goes bankrupt, or their website goes down, then the rest of the service remains intact. For example, if GMail suddenly has a long outage, all of the GMail users cannot use email, but everyone on Outlook can still send emails to accounts on Yahoo Mail. In other words, federated services are more resiliant. The second reason is related to privacy and trust; users must trust the owners of whatever service they use to handle their information wisely. Many people have felt that Facebook violates their privacy by performing analytics on their social media activity and then selling the results for profit. While federation does not remove the need for users to trust their service provider, it does lower the impact that a maliciously intending service provider might have. For example, on Mastodon, there are many instances (service providers) that have about 200 users; if the owner one of these instances decides to misuse its users information, the users on other instances are relatively unaffected. Put shortly, federation is often, though not guaranteed to be, the better option for achieving privacy and staying safe on the internet.
It is not always easy to start using federated services, since the majority of people use their centralized alternatives. A good way to begin is to find a group of people that will use the service within each other. For example, I’ve begun using Matrix with my parents and some of my friends. Although with a small group, the benefits are not very significant (and it may be inconvenient at times), we can hope that federated services will become more prevalent in the coming decades.