GIS Geographic Information System
Systems for storing, analysing and visualising data that has a location.
Two base data types: vector (points, lines, polygons — parcels, roads, boundaries) and raster (grids of cells — satellite imagery, elevation models). Analysis consists of combining layers: which buildings lie within 100 metres of the shoreline?
The perennial pitfall is projections. The earth is round, the screen is flat, and every projection sacrifices something — area, shape or direction. EPSG codes identify which coordinate system applies, and mixing them up is the GIS world's equivalent of mixing up time zones. Tooling: PostGIS, QGIS, GDAL.