A Geographic Information System (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present all types of spatially-related data.
Most observational data has some spatial element (everything happens somewhere!) and can be in some way analyzed based on geographic conditions and proximity
GIS falls within the geospatial umbrella that also encompasses remote sensing and field data collection methods such as GPS, the use of drones and satellite imagery. Most industries and academic disciplines have some areas of research relying on types of GIS.