Nobody knows. It's a mystery.  

 You can think of nostr as passing notes in class. Relays are the desks in between who "pass it on". 

Every time I post a note or comment or anything on nostr, that gets sent to the relays I'm connected to. Those relays then serve up my note to everyone else that's also connected to that relay.  

 nostr:note18pdj7lteu4vd58s8ecl54sxd8suqzhqxkyjztflt50jl099eh90s6vdwks 

 nostr 🔎 "relay" 
https://nostrcheck.me/media/5e5fc1434c928bcdcba6f801859d5238341093291980fd36e33b7416393d5a2c/3376f0428c4afad86cbd9786291bab323931e95131a871bb5a33ca0f0d36cccc.webp 

 Think of it as a server that sends a message to other servers. The more servers(relays) you have connected, the less likely you can be censored. They would have to take down all those servers (relays) you connected to in order to censor you. 

 🫂 

 https://nostr.how/en/relays
https://voltage.cloud/blog/nostr/the-essential-guide-to-nostr-relays/ 

 It's just a server that you connect to. Check my notes. I have a banger explanation from earlier today.