Technology glossary

Geodesy

Geodesy is the science of measuring Earth's shape, orientation, gravity field and changes over time. Satellite navigation systems such as GPS became powerful geodetic tools for tracking tectonic motion, surveying and maintaining precise reference frames.

Geofencing

Geofencing creates a virtual boundary around a real-world location so software can trigger an action when a device enters, leaves or remains within that area. It commonly relies on GPS, other GNSS signals, Wi-Fi or cellular positioning.

Geographic Atrophy

An advanced form of dry age-related macular degeneration involving loss of retinal cells.

Geolocation

Geolocation is the process of determining the geographic location of a device or object using signals or data such as GNSS, cellular networks, Wi-Fi, IP information or nearby beacons.

Geological Carbon Storage

The injection and monitored containment of carbon dioxide in deep porous rock formations beneath impermeable sealing layers.

Geospatial Misinformation

False or misleading content that uses maps, coordinates, satellite imagery or other location data to support an inaccurate claim about a real place or event. It can combine genuine geographic context with altered, outdated or fabricated visuals.

Geostationary Satellite

A geostationary satellite orbits above the equator at the same angular rate that Earth rotates, so it appears fixed over one longitude. Such satellites are used for communications, weather observation and GNSS augmentation services.

Geotagging

Geotagging attaches geographic coordinates or place information to digital content such as photographs, videos or posts. Phones commonly obtain the coordinates from GNSS or other location services when the content is created.

Giant Unilamellar Vesicle(GUV)

A cell-sized spherical compartment enclosed by one lipid bilayer. Researchers use giant unilamellar vesicles as simplified membrane models because their composition can be controlled and their contents can be observed with light microscopy.

Gigaelectronvolt(GeV)

A gigaelectronvolt is a unit of energy equal to one billion electronvolts. Particle physicists use GeV to describe the energy or mass scale of subatomic particles; muons carrying several GeV have enough penetrating power to traverse substantial shielding and dense objects.

Globular Cluster

A dense, roughly spherical collection of thousands to millions of stars bound together by their own gravity, typically orbiting a host galaxy such as the Milky Way.

GLONASS(GLONASS)

GLONASS is Russia's global satellite navigation system. Like GPS, it provides positioning, navigation and timing, and many consumer receivers combine its signals with other GNSS constellations to improve satellite availability.

Gluon

A subatomic particle that carries the strong nuclear force, binding quarks together inside protons, neutrons, and other particles made of quarks.

Glycated Haemoglobin(HbA1c)

A blood measurement that reflects average glucose levels over roughly the previous two to three months and is widely used to monitor diabetes control.

Glycocalyx

A coating of sugar-based molecules on the outside of cells, found on healthy and cancerous cells alike, that cancer cells can thicken to hide from the immune system.

GNSS(GNSS)

GNSS (Global Navigation Satellite System) is the general term for satellite constellations that provide positioning, navigation and timing, including the U.S. GPS, Europe's Galileo, China's BeiDou and Russia's GLONASS.

GNSS Receiver

A GNSS receiver processes radio signals from navigation satellites to estimate position, velocity and time. Modern receivers often track several constellations and multiple frequencies while combining satellite data with other sensors.

GPS(GPS)

GPS (Global Positioning System) is the United States' satellite-based positioning, navigation and timing system. Receivers calculate position and precise time by comparing radio signals from multiple satellites carrying synchronized atomic clocks.

GPS III

GPS III is a generation of U.S. Global Positioning System satellites designed to provide improved accuracy, stronger signals, longer design life and modern military and civilian capabilities, including M-Code and the interoperable L1C civil signal.

GPS Jamming

GPS jamming is deliberate or accidental radio interference that overwhelms weak satellite navigation signals and prevents a receiver from obtaining a reliable position or time solution.

GPS Spoofing

GPS spoofing is the transmission of counterfeit navigation signals designed to make a receiver calculate a false position or time. It differs from jamming, which attempts to block or overwhelm genuine signals.

GPS Time

GPS Time is the continuous time scale used by the Global Positioning System. It began in January 1980 and does not insert leap seconds, so navigation messages provide information that lets receivers relate GPS Time to UTC.

GPS Week Number Rollover

GPS Week Number Rollover is a date-handling event caused by older GPS navigation messages storing the week count in a limited number of bits. Legacy receivers that do not handle the rollover correctly can calculate the wrong date even when positioning signals remain available.

Graph Neural Network(GNN)

A neural network designed to learn from data represented as nodes and connections, making it useful for molecules, materials, transport networks and other relational systems.

Gravitational Microlensing

A temporary brightening that occurs when a foreground object's gravity bends and magnifies light from a more distant star. A planet around the foreground object can add a short feature to the light curve, revealing worlds that may be difficult to find by other methods.

Gravitational-Wave Recoil

A kick imparted to a merged black hole when gravitational waves carry momentum away asymmetrically.

Green Ammonia

Ammonia produced with very low greenhouse-gas emissions, typically by using renewable electricity to make hydrogen or directly drive electrochemical synthesis. The label describes the production route, not a different chemical form of ammonia.

Grid Capacity

The amount of electrical power a grid can generate, transmit, distribute, or connect reliably within technical and safety limits. Available capacity varies by location and time and can be constrained by generators, lines, transformers, voltage, stability, or demand peaks.

Grid Flexibility

The ability of an electricity system to adjust production, consumption, storage and power flows as conditions change. Flexible demand, batteries, dispatchable generation and stronger transmission can help keep supply and demand balanced.

Gross Dies per Wafer

The theoretical or physical count of chip dies laid out on one silicon wafer before failed units are removed. It indicates packing density and potential output, but it is not the same as the number of saleable chips.