What are Geographic Information Systems (GIS)?

Stephen Anderson
5 min readDec 11, 2020


And what do they do? 🌎

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I recently interviewed for a Software Engineering position with a company that specializes in Geographic Information Systems (GIS). Before researching this company, I had never even heard the term, but after looking into the company I was blown away by the product they had created and what it could do. When interviewing with the company I learned even more about GIS and how it's made and what it's used for, this really piqued my interest so I had to learn more! This is what I found.

No seriously… what is it?

The best definition of GIS that I found was actually from the University of Wisconsin-Madison, “A geographic information system (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present all types of geographical data. The key word to this technology is Geography — this means that some portion of the data is spatial. In other words, data that is in some way referenced to locations on the earth.” In even simpler terms its software used to store, visualize, analyze, and interpret geographic data. The “store” aspect is referring to large database tables full of information and the “visualization” aspect is simply referring to maps. The data is usually brought in by layers and from various sources where it is aggregated into one system, the GIS.

Data layers in a sample GIS system

What is it used for?

Well, the obvious answer is analyzing data, but what kind of data? And what is that data used for? It really depends on the industry in which GIS is being utilized. Here are a few:

  • Real Estate — Land parcels, Market prices by region
  • Education — Academic performance by region
  • Health — Tracking the spread of a deadly virus 🙄
  • Insurance — Risk probability by region
  • Public Safety — Real-time situational data for first responders
  • Transportation — Traffic patterns, Mapping your commute routes
  • Government — Population, mapping of congressional districts
  • Sustainability — Display areas where humanitarian assistance is needed

and many, many more….

GIS system tracking confirmed COVID-19 Cases

How did it come about?

One of the most famous early examples of spatial analysis can be traced back to London in the year 1854 when Dr. John Snow (no not the one that is King of the North) was able to predict the occurrence of the cholera outbreak. Thanks to the study that Snow released, officials from the government were able to determine the cause of the disease; which was contaminated water from one of the major pumps. The map that Snow came up with was very interesting in that it had the capability of analyzing the phenomena relating to their geographical positions and this was the first time the world was witnessing this.

John Snow’s Cholera Map

Of course, this was a manual way of performing the analysis and we can do studies like this much quicker with the use of computers. But it is still the same method that started the whole thing nonetheless.

How does it work?

The core of a GIS system is its data, the data is where you get the information that is to be visualized and is the “store” aspect that we have mentioned before. The data will always include a location as well as other pertinent information. The core of the visualization is the map, the map will take the data and visually present it in a manner that can be analyzed. In other words, it will take the location information from the data and plot it for you. The final part is why we even do the first two steps, the analysis. The analysis uses the collected and visualized data to find answers, trends, or even forecast the future. It is the core of why GIS exists, and why it is an industry that is getting bigger by the day.

Tech’s role in GIS

The heart of a modern GIS system is indeed software. You will need databases to hold the data, a backend to process that data and perform analysis, and a frontend to visualize the data and the analysis results. Luckily, Software Engineers are a generous and caring group so many things are open source. Here are a few open-source tools used in GIS:

  • OpenLayers — Open source Javascript library for displaying map data in web browsers.
  • Leaflet.js — Open source Javascript library used to build web mapping applications.
  • PostGIS — Open source software that adds support for geographic objects to a PostgreSQL database.
  • SpatiaLite — Open source extension that provides vector geodatabase functionality for SQLite databases.

There are also paid services that provide GIS capabilities in niche areas as well.

The Wrap-Up

GIS has become more and more of an essential tool as time passes and its industry is growing with it. GIS tech companies will continue to grow, making the capabilities of GIS grow, making the chances of discovering world-changing data grow. I hope you enjoyed reading this as much I did writing it!



Stephen Anderson

Hi, I’m Stephen! I’m a Software Engineer just trying to help people through applications that make the world better. Check me out at stephenanderson.dev.