What is GIS?

It is easy to confuse GPS and GIS, but they perform two entirely different jobs.

• GPS : Uses satellites to give you a raw, exact coordinate on the Earth. It tells you where you are.

• GIS: Is the computer software system used for capturing, storing, checking, integrating, manipulating, analyzing, and displaying that spatial data. It tells you what is there and how it connects to everything else.

Unlike a traditional paper map where all information is permanently printed on a single flat surface, GIS builds maps using individual Data Layers.

A spatial analyst begins with a foundational base map (such as a satellite image or basic street map) and stacks separate, transparent layers of specific data on top of it. Each layer represents a single geographic theme. For example, one layer might show only roads, another only building footprints, and a third only population density.

By turning these different layers on, off, or blending them together, professionals can analyze how different geographic elements interact to solve complex problems—like stacking a "Real-Time Traffic" layer over an "Emergency Routes" layer to find the fastest path for an ambulance.

To build these layers, GIS software uses two main types of data:

1. Vector Data: Precise, mathematical graphics used to represent distinct features. It comes in three simple forms:

   • Points: Marks a specific, exact location (e.g., a single tree, a fire hydrant, or a crime scene).

   • Lines: Marks a continuous path (e.g., a river, a highway, or an underground gas pipe).

   • Polygons: Marks an enclosed area or boundary (e.g., a lake, a school property boundary, or a voting district).

2. Raster Data: Continuous data made up of a grid of pixels. It is used to show information that covers a massive area without distinct borders. Examples include satellite photographs or weather radar heat-maps.