The document traces the evolution of beacon technology from 2013-2016, including key developments such as: - Apple's announcement of iBeacon technology in 2013 which used coin cell batteries - Vendors switching to larger AA battery powered beacons in 2014 - Google creating UriBeacon to connect Bluetooth Low Energy beacons to the Physical Web in 2015 - Google launching the open Eddystone beacon format in 2015 to support both iOS and Android platforms - Predictions that beacon sales will influence over $40 billion in sales by 2016 and shipments will exceed 400 million units by 2020