It's the hole in the wall that gives you internets.
Discussion
If you mint a nut today, your wallet will request an invoice from the mint and then constantly ping the mint whether it has been paid yet or not. This is called polling.
With WebSockets a bidirectional communication is established, so that the mint can simply ping the wallet once the invoice is paid
for the record, I was joking https://emojipedia.org/face-with-tears-of-joy