Wi-Fi is the signal that lets your devices connect wirelessly to the nbn/internet around your property. nbn is the National Broadband Network that connects your property to the internet. For most properties, this happens via lines of cable or other types of wiring under your street. A third type of connection is wireless or mobile broadband, which uses the same type of mobile network you use to access the internet via your smartphone (3G, 4G, or 5G).