A Scanner is any device (phone, tablet, etc.) that utilizes and runs the Ingress app. The Main Screen displays the map area the agent is in range to detect with the scanner. Detectable assets include Portals (green, blue, or white), Shields, Resonators, Links, Control Fields, any Item on the ground and Exotic Matter (XM) all seen over a simple, dark themed map showing roads and major buildings. The Main Screen also provides the compass, the agent's current position, area of influence, XM reserves, level, level progress (Access Points), avatar and access to OPS and COMM.
The influence area has a 40 meter radius. An agent cannot do most functions with a portal unless the portal is with their influence area. One exception is Recharging a portal remotely.