Merchant will create items and associate a QR code ([a LNURLp](https://github.com/lnbits/lnbits/blob/master/lnbits/extensions/lnurlp/README.md)) with a price. He can then print the QR codes and display them on their shop. When a customer chooses an item, scans the QR code, gets the description and price. After payment, the customer gets a confirmation code that the merchant can validate to be sure the payment was successful.
- Wordlist is the default option: after a successful payment the customer will receive a word from this list, **sequentially**. Starting in _albatross_ as customers pay for the items they will get the next word in the list until _zebra_, then it starts at the top again. The list can be changed, for example if you think A-Z is a big list to track, you can use _apple_, _banana_, _coconut_\
- TOTP (time-based one time password) can be used instead. If you use Google Authenticator just scan the presented QR with the app and after a successful payment the user will get the password that you can check with GA\