So once you’ve posted something, you can never delete it?  (I know nothing is ever “really deleted” on the internet… but my point is this is different from other social media platforms) 

 There are some clients that allow you to request that a note gets deleted, but there is no guarantee that the relays will actually follow through with the request.

Some relays also prune notes older than a few months to save on storage space, but the paid premium relays usually don't delete anything. 

 Got it. I’ve downloaded a few clients to try them out.  They all seem to use different relays.  Is there any reason to add more relays to my preferred client?  What’s the benefit of a paid relay? 

 Only for more reach. Paid relays help with preventing spam by requiring the account to go through a pay wall to join. 

 Anyone and everyone can run their own Nostr server if you'd like. Discord is similar in this regard, but it's all  Discord's servers with their rules and their guidelines. Nostr is different because there is no central company that is in control. Users are in control. It's a protocol built by users for the users. 

 It's still more like Twitter/X or Facebook, except instead of sending/receiving posts through just their servers, you send/receive to many servers run by multiple people 

 The main difference is that you can physically own and control your own relay. Discord can shut down your server on a whim. Nostr cannot.