Skip to content

GIS Fundamentals

Goal: Understand what a Geographic Information System is, what it can do, and why it's a uniquely powerful way to look at data.

What you'll learn

  • What GIS actually is (and isn't)
  • The four components of every GIS
  • Why spatial data is different from regular data
  • Where GIS is used in the real world

What is GIS?

A Geographic Information System (GIS) is a system that lets you store, view, analyze, and share data tied to a location on Earth.

Unlike a spreadsheet, where each row is just a record, in GIS each row is also a shape on a map — a point, a line, or a polygon. That single fact unlocks a huge category of questions:

  • Where are the new customers concentrated?
  • How far is each school from the nearest fire station?
  • Which parcels are inside the floodplain?
  • What happens to traffic if we close this bridge?

The four components of GIS

flowchart LR
    H[Hardware] --> S[Software]
    S --> D[Data]
    D --> P[People &<br/>Methods]
    P --> H

    classDef box fill:#eef2ff,stroke:#4338ca,color:#312e81
    class H,S,D,P box
Component Examples
Hardware Your computer, GPS units, drones, servers
Software ArcGIS Pro, ArcGIS Online, QGIS, PostGIS
Data Shapefiles, GeoTIFFs, feature services, CSVs
People & methods Analysts, cartographers, workflows, standards

How GIS data is different

A spreadsheet row:

city population
Atlanta 498,715

A GIS row:

city population geometry
Atlanta 498,715 POLYGON((-84.55 33.65, -84.29 33.65, ...))

That extra geometry column is the magic. It lets the software draw the city, measure its area, find what's inside it, and compare it to other shapes.

Two parts of every GIS feature

  1. Geometry — where it is (point, line, polygon, or pixel)
  2. Attributes — what it is (name, type, population, value…)

Where is GIS used?

  • Urban planning

    Zoning, transit, density, growth boundaries

  • Environment

    Wildfire risk, flood zones, biodiversity, air quality

  • Logistics

    Routing, delivery zones, store siting, supply chains

  • Public health

    Disease mapping, hospital access, emergency response

  • Utilities

    Power, water, gas, telecom infrastructure

  • Government

    Census, parcels, public safety, voting districts

Vector vs raster (preview)

You'll see these two words constantly. Quick preview:

  • Vector — discrete shapes (a road, a building, a state)
  • Raster — a grid of pixels (satellite imagery, elevation)

→ Full breakdown in Vector Data and Raster Data.

What GIS is not

Common misconceptions

  • GIS is not just "making maps." Maps are the output; analysis is the value.
  • GIS is not Google Maps. Google Maps is a consumer product. GIS is a professional analysis platform.
  • GIS is not only for geographers. Engineers, planners, biologists, marketers, and emergency responders all use it.

Practice

Try this

  1. Open ArcGIS Online (free public account).
  2. Click Map.
  3. Search "Atlanta, GA" and zoom in.
  4. Click Add → Browse Living Atlas Layers and add a population layer.
  5. Click on a feature. Notice the attribute popup — that's the row of the spreadsheet behind the polygon.

You just used a GIS.

Next up

→ Maps & Spatial Thinking — train the spatial mindset.