Technology now enables us to identify, quantify, and classify information about the world and about ourselves. This data is often meaningless without location, or takes on new meaning when location is considered. As data within context becomes information, data within a geographic context becomes geographic information. GIS, or Geographic Information Science, is the study and manipulation of that information in a real-world, spatial context.
A physical geographer studies data revealing information about places such as altitude, rainfall, aspect, soil composition, underlying geology, temperature, agriculture, land use, vegetation cover, snowfall, and presence of water.
Demographers study the distribution and patterns of social factors such as poverty, homelessness, education, employment, disease, access to water, childhood mortality, and population.
GIS allows scientists to overlay combinations of these social and environmental factors in order to explore patterns that may only be revealed when place is included.
Increasingly, data is captured by sensor. Satellite imagery, LIDAR, wildlife cameras, seismometers, weather balloons, bouys, and weather stations capture petabytes of data pertaining to the physical world. This Big Data is massive and usually resides with the originating agency. Another type of sensor, though, is becoming more and more popular. With the rise of cellular networks and mobile devices, social media is now one giant sensor for social (and often physical) data. GIS is rapidly absorbing this Big Data, developing data mining and georeferencing techniques that allow citizens to provide this data without even realizing it.