According to the Environmental Protection Agency, a GIS, which refers to Geographic Information System, works by combining database functions with computer mapping to map and analyze geographic data. It uses a "layering" technique to combine various types of data. Special GIS software is used to analyze layered data and create new layers of data.
Amanda Briney explains on About that GIS is a tool used by analysts and geographers to visualize data in various ways to view patterns and relationships in a specific area or subject. Typically, these patterns are found on maps, but they also appear in reports and charts and on globes. A GIS gathers information from multiple sources and enables a variety of work to be accomplished. To do this, the data is normally tied to a particular region on the Earth’s surface. Generally, latitude and longitude are used, and the locations are connected to their points on the geographic grid.
Briney further explains that to perform an analysis, a different set of data is layered on top of the first set to see spatial patterns. The Environmental Protection Agency details that when studying data through spatial analysis, GIS validates theories and explores trends and patterns. For example, with the help of demographic data, plant monitoring locations, and emissions, a user buffers all plant locations by specified distances to assess the relation of emissions to health in surrounding populations.