What is “Pleroma”
Pleroma is a federated social networking plattform, which is licensed under the AGPLv3 free software license.
What is a federated social network?
A federated social network is distributed on many servers, rather than on one central server like Twitter or Facebook. And each server hosts individual users and their content. It is decentralized like e-mail. And also like in an e-mail adress, you’ve got a unique address (e.g. @firstname.lastname@example.org).
These servers or “instances” are connected to each other. So users of a federated social network can follow each other, regardless which instance they use. This leads to a connected social network universe which is also greatly named “Fediverse” (federated universe). But it still differs (a lot) from a central social network. The Fediverse isn’t and can’t be controlled by any instance.
Pleroma is not the only project which is connected to the Fediverse. There’re more (great) projects out there like Mastodon, GNUSocial or Friendica!
Our own Pleroma instance
We’ve also got our own pleroma instance named “TorominoSocial” (very creative, I know) at https://social.toromino.de. TorominoSocial is community instance with open registrations.