Decoding Data Types

As you might imagine, data comes in many shapes and sizes and with that comes file extensions! Here are the most common ones that you might run into. This section can serve as a reference on your mapping journey.

Attribute Data File Types and Software

• Attribute data are stored in a table with rows and columns. This is often called a tabular dataset.
• A Comma-Separated Values file, or CSV, is the most common file type you'll see for attribute data.

File Type	Extension	Description
Comma Separated Value	.csv	tabular data file usually with geometry id and characteristics of each geometry

• You can open and read a CSV file in Excel or Google Sheets

Consider this: How might these various file types and data collection and storage methods introduce bias?

Spatial Data File Types and Software

• Common spatial file types include Shapefiles, GeoJSON, and GeoTIFF
• Each file type stores geographic data in a different way and is used in specific circumstances (recall vector vs. raster!)
• GIS software is used to view and edit these data types; there are desktop programs like QGIS and web-based programs like Carto.

File Type	Extension	Description
Shape File	.shp	contains feature geometry and attributes together; often a bundle of separate files each of which contains different information, like projection
GeoJSON	.GEOJSON	JavaScript-based vector geometries (i.e. points, lines, and polygons); good for web-mapping, i.e. mapping on a browser-based platform like Google Maps and Carto
GeoTIFF	.TIF	standard raster file type for satellite and GIS images

More resources on file types and software