Plebbit is a selfhosted, opensource, nonprofit social media protocol, this project was created due to wanting to give control of communication and data back to the people.
Plebbit only hosts text. Images from google and other sites can be linked/embedded in posts. This fixes the issue of hosting any nefarious content.
ENS domain are used to name communities.
Plebbit currently offers different UIs. Old reddit and new reddit, 4chanw, andhave a Blog. Plebbit intend to have an app, internet archive, wiki and twitter and Lemmy. Choice is important. The backend/communities are shared across clients.
There's an XKCD for that, although i do think ActivityPub could be improved.
It's not a competing standard, it's a whole new approach to decentralize forum-based social media.
ActivityPub is not fully decentralized, it's a federated design, meaning it's a network of instances, and each instance is just a regular website with servers. Anyone can run an instance, but it's expensive, tiresome and you'll get banned for it; they are regular websites.
whereas Plebbit is fully decentralized, it's purely peer to peer, meaning it's a network of peers where every peer can potentially be a full node by simply using the desktop app (or in the future, a non custodial public rpc on mobile), and you don't have to run any site/domain for it, it's censorship resistant just like running a torrent with a BitTorrent client.
Also to be clear: like ActivityPub is a protocol with clients, such as Mastodon and Lemmy, Plebbit is a protocol with clients, such as Seedit and Plebchan.
So technically Plebbit is distributed then ?
Yes. Reddit is A, ActivityPub (Lemmy, Mastodon) is B, Plebbit (Seedit, Plebchan) is C:
How does it compare against let's say Steemit ?
Steemit is A, it's a regularly centralized website with global admins, claiming to be "decentralized" simply because it's built on a blockchain. Whenever you are asking yourself whether something is "decentralized" or not, ask "how can I run a full node"? "What are the hardware requirements"? Steemit admins won't answer those questions. Whereas you can easily spin up your own ActivityPub (Mastodon or Lemmy) instance (even though those instances work like regularly centralized websites, at least you have the option to run your own).
On Plebbit, just using the desktop app of a client (like Seedit's desktop app you can download here means you are running a full node already. The app runs an IPFS node in the background, seeding all content you browse automatically, thereby improving the speed of the network for everybody else. The more nodes there are, the more decentralized the network is, so if all users can easily run a node and are incentivized to do so, then the network is properly decentralized/distributed. On Seedit, you can't run a community if you don't run a full node (the community is the node, acting like a server, and users connect to it P2P). There are no global admins.