Wi-Fi location, sometimes known as 'Wi-Fi sniffing' is a method to get location using the different Wi-Fi access points in the vicinity of the TrackALL device. The device does not connect to the Wi-Fi networks, instead, it captures the MAC address and the RSSI of the different Wi-Fi access points it ‘sees’. Then, using mcAir or Sigfox, you can send that information to the cloud and parse it through a location service like Google or Skyhook. Those location services have an incredibly large database of locations of different Wi-Fi access points. The information provided by the TrackALL allows those databases to provide a relatively accurate location based on the signal strength to those Wi-Fi access points. That location information can then be plotted onto a map.
The accuracy is subjective to how many access points are in the vicinity of the devices. If you are in a saturated area and those Wi-Fi access points are in the database of the location service, you could get as accurate as +-10-15m (possibly better). If you are in an area with limited Wi-Fi access points, you may have a less accurate location. The great thing about Wi-Fi location is that it is MUCH less power than using a GPS location system and allows you to do indoor locations as you don’t require a view of the sky!