This book is focussed on looking into the various commercially available location tracking technologies that may prove a best fit for tracking visitors in large indoor public spaces which allow clients to ascertain footfall, repeat visits and dwell time. The systems which are potentially suitable must be capable of "Presence Identification". That is the identification of a customer upon entry in a physical retail environment and "session-metrics" which is the shopping pattern of a customer in a physical store including time of entry/exit. Two main technologies are most suitable for this - active RFID and WiFi. Active RFID systems installed at the entrance of shops are able to conclusively identify a card/tag carrying customer upon entry. The customer would not have to produce a card if the card was present on a shopping trolley. The read range of the portal would be adequate if placed near a doorway. In order to capture session metrics an active RFID system would also capture the exit of the customer through the portal. WiFi localisation systems would also track an active tag or mobile device but would not require the installation of portals at doorways.