This glossary includes key terms of the IoT (Internet of Things) & M2M (machine-to-machine) communications industry, including wireless and cellular technologies spanning many different markets. It is updated to present current terminology and usage. Your participation and feedback are most welcome—to submit comments, new entries, or suggestions, contact us today.

# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
There are 17 names in this directory beginning with the letter G.
Galileo
Developed by the European Union and Space Agency, Galileo is a global positioning constellation of satellites which is still in development and will be made up of 30 satellites (27 operations and thee active spares).
Gateway
A link between two computer systems or programs. This way they can share information with each other. The router for your home Internet is one type of gateway.
General Packet Radio Service (GPRS)
A wireless communications standard on 2G and 3G cellular networks which supports a number of bandwidths and provides data rates of 56-114 kbps. As cellular companies move to more advanced networks, GPRS networks may be more cost-effective for IoT networks.
Geofence
A virtual border applied to a physical space. For example, geofencing might be defined around a nursery, and when a mobile device crosses the nursery boundary, an alert is generated. Geofences may be dynamically created and in a telematics application can encompass entire neighborhoods or cities.
Geographic Information System (GIS)
The combination of hardware, software, and data that captures, manages, analyzes, and presents many kinds of geographic data. GIS and location intelligence applications can be the foundation for location-enabled services.
GeoJSON
A dialect of JSON that describes physical places. Features modeled by GeoJSON are points, line strings, polygons, and multipart groups of these types (MultiPoint, MultiLineString, MultiPolygon). Numerous mapping and GIS software packages employ GeoJSON.
Geotagging
The process of tagging a photo, video, or other types of media with coordinates, thus marking it with a location.
GGSN
Gateway GPRS Support Node (see also SGSN).
GIS
Geographic Information System.
Global System for Mobile communication (GSM)
This is the most widely used digital cellular network and the basis for mobile communication such as phone calls and the short message service (SMS).
GLONASS
The Russian global navigation satellite system with a constellation made of 24 satellites orbiting Earth. These multi-constellation GPS modules allow users to access multiple satellite networks, and accessing extra satellites allows for faster and more accurate positioning as well as offering greater resilience when satellites are obscured in areas such as cities.
GNSS
Global Navigation Satellite System. Used when talking about different constellations of satellite navigation systems.
GPRS
General Packet Radio Service.
GPS
Global Positioning System. A system of satellites and radio transmissions that can be used to locate GPS-enabled hardware anywhere on the planet to a very good accuracy.
Greenfield
In contradiction to brownfield, a greenfield project is a one where no consideration of previous systems is needed, thus already existing standards can be ignored.
GSM
Global System for Mobile communication.
GSM MAP
GSM Mobile Application Part, for control signal messaging on SS7.