There are more than 250 applications for android to scan QR and classic bacodes what sign its popularity. Mobil companies are tend to integrate to the devices also widely use in trading and manufacturing.
Online QR code generator can create various messages to the visitors: Phone number, best offer, Review me!, giving Wifi settings, etc.
This makes the online communication effective.
This is the code of my Polish phone number:
Or this is a Youtube channel about best tourist attractions in Kraków