Density measures foot traffic to and from brick and mortar business. Density is a door sensor which tracks foot traffic with infrared beams. It tracks by listening to the smartphone's wifi address or MAC address. Provides an iOS app for the merchant that functions as his foot traffic dashboard. Merchant can view detailed analytics about the number of visitor per day, unique visitors per month etc. and can reach up to other merchants they share customers with and offer deals based on that data. Provides the device for free and charges $50 per month for the service.