Beginner's Guide to GIS
IntroductionStart here
What is GIS?6 min read · What GIS actually means, what it does, and how to tell whether you need it.
GIS Mapping10 min read · The common map types (category, quantity, heatmap) and how data-driven styling works.
GIS Data9 min read · Vector vs raster, shapefiles and the other formats, and how to source and prepare data.
GIS Software12 min read · Desktop, web, and server GIS, plus a hands-on tour of the essentials.
Web GIS6 min read · Sharing maps online, story maps, and where web GIS fits alongside the desktop.
Common Mistakes Beginners Make7 min read · The handful of classic beginner errors that make maps misleading, and how to sidestep them.
Make Your First GIS Map8 min read · A hands-on walkthrough, from a starter dataset to a styled, shareable interactive map.
Glossary & Cheat Sheet4 min read · Key GIS terms, common file formats, handy EPSG codes, and the decision tables in one place.
Chapter 8 of 8
Glossary & Cheat Sheet
Key GIS terms, common file formats, handy EPSG codes, and the decision tables in one place.
Keep this chapter bookmarked. It gathers the terms and tables from the rest of the guide into one place, so you can check a definition or make a quick decision without hunting through the chapters.
Key terms
| Term | In plain English |
|---|---|
| GIS | Geographic Information System: software for mapping and analysing location data |
| Feature | A single thing on the map: one state, one shop, one river |
| Attribute | A column of data about a feature, such as its name, value, or category |
| Layer | One dataset drawn on the map; maps are often several layers stacked |
| Point | A single location (a coordinate), like a shop or a bus stop |
| Line | A connected series of points, like a road or a river |
| Polygon | A closed loop of lines, like a country border or a parcel |
| Vector | Data stored as points, lines, and polygons (instructions for drawing) |
| Raster | Data stored as a grid of pixels, such as imagery or elevation |
| Projection | A way of flattening the 3D earth onto a 2D map (always adds some distortion) |
| CRS | Coordinate Reference System: how coordinates map to the real world |
| EPSG | A short numeric ID for a specific coordinate system |
| Geocoding | Turning an address into map coordinates |
| Spatial join | Matching records by location instead of a shared value |
| Basemap | The background map (streets, satellite) that gives your data context |
| Tile | A small, pre-cut piece of a map, fetched as you pan and zoom |
| Choropleth | A map that shades areas by a value (best used with rates, not raw totals) |
| Heat map | A map that reveals density in dense point data |
| Web map | An interactive map published online, viewable in a browser |
Common file formats
| Format | In plain English | Good for |
|---|---|---|
| CSV | A spreadsheet with coordinates or addresses | Simple point maps |
| GeoJSON | A web-friendly spatial data file | Small to medium web-map layers |
| Shapefile | Very common older GIS format, made of several files | Legacy data exchange |
| GeoPackage | Modern single-file GIS database | General-purpose storage and sharing |
| GeoTIFF | Raster data with its location baked in | Imagery, elevation, scanned maps |
| Vector tiles | Pre-cut web-map data | Fast interactive web maps |
Handy EPSG codes
| EPSG | Name | Units | You'll use it for |
|---|---|---|---|
| EPSG:4326 | WGS84 (lat/long) | degrees | GPS coordinates, sharing point data |
| EPSG:3857 | Web Mercator | metres | Slippy web maps and basemaps |
Which map type? (quick reference)
| What you want to show | Good map choice | Watch out for |
|---|---|---|
| Exact locations | Point map | Overlapping points |
| Lines or routes | Line map | Thickness implying false importance |
| Values by area | Choropleth | Raw counts instead of rates |
| Intensity or concentration | Heat map | Hiding individual records |
| Quantity at locations | Proportional (bubble) symbols | Symbols swamping the map |
| Categories | Categorical colours | Too many categories |
| Change over time | Time slider / small multiples | Flashy animation over clarity |
| Distribution across areas | Dot density | Dots read as exact addresses |
Before you publish (checklist)
- Is the map normalised where it needs to be (rates, not raw counts)?
- Is the map type right for what you're showing?
- Are the colours ordered and colour-blind-safe?
- Is it free of clutter, with one clear message?
- Have you checked the data's source, date, and licence?
- Is it optimised enough to load quickly?
- Does it work on a phone, for the people who'll actually use it?
That's the whole guide in a nutshell. Refer back any time, and go make some maps.
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