Seems like it's federated and if you really connect with someone you meet, you can probably choose to become "friends" and store each others' directly, bypassing that federated/centralized server.
SSB as a technology is about as decentralized as it gets.
All posts are stored locally, you can write posts and replies and do everything offline. Then when you share some medium with other peers, they gossip all their updates, as well of the updates of their friends and friends of friends.
That medium can be a shared wifi (if it allows UPD multicast) or it can be bluetooth (only for manyverse so far... desktop bluetooth gossip is haaaard) but at the moment, the shared "medium" is often an internet server.
These servers ("pubs") are not any different from normal ssb peers, they just expose a public IP and don't have NAT.
There's two issues that people take with pubs:
1. They make the ecosystem less decentralized, moving it more towards a sort of federation. But it's not like you only connect to the pubs you select. Usually an ssb application will connect to many different pubs that it knows about, so there's no single point of failure there.
2. Following a pub means that you get blasted with a fire hose full of random strangers' (everyone who signed up for that pub, plus their friends) posts, which take up space on your drive, and (more importantly) need to be verified and indexed locally. That makes onboarding very slow and tedious, especially on mobile devices.
Rooms relate to the latter. They're an easy way to have a pub server that only connects you to the group of people you want to be connected to. Well, if you don't share invites to it around freely that is. And it's simple to set up, even for less technical people. Maybe think of it like a NAT traversal with extra crypto.
Like that, onboarding a friend onto SSB is a bit more elegant: you still give them an invite, but to a room for a social circle that they already fit into, or even a room just for you and them. Now instead of having to let the device sit and digest a thousand feeds over night, it only gets the feeds they would want to know about. It's much more like local off-grid onboarding.
That medium can be a shared wifi (if it allows UPD multicast) or it can be bluetooth (only for manyverse so far... desktop bluetooth gossip is haaaard) but at the moment, the shared "medium" is often an internet server. These servers ("pubs") are not any different from normal ssb peers, they just expose a public IP and don't have NAT.
There's two issues that people take with pubs:
1. They make the ecosystem less decentralized, moving it more towards a sort of federation. But it's not like you only connect to the pubs you select. Usually an ssb application will connect to many different pubs that it knows about, so there's no single point of failure there. 2. Following a pub means that you get blasted with a fire hose full of random strangers' (everyone who signed up for that pub, plus their friends) posts, which take up space on your drive, and (more importantly) need to be verified and indexed locally. That makes onboarding very slow and tedious, especially on mobile devices.
Rooms relate to the latter. They're an easy way to have a pub server that only connects you to the group of people you want to be connected to. Well, if you don't share invites to it around freely that is. And it's simple to set up, even for less technical people. Maybe think of it like a NAT traversal with extra crypto. Like that, onboarding a friend onto SSB is a bit more elegant: you still give them an invite, but to a room for a social circle that they already fit into, or even a room just for you and them. Now instead of having to let the device sit and digest a thousand feeds over night, it only gets the feeds they would want to know about. It's much more like local off-grid onboarding.