Slippy map tiles are square or rectangular images that follow a coordinate system defined by a grid called
Tile Matrix: docs.opengeospatial.org/is/17-083r2/17-083r2.html. The
Web Mercator grid is the de facto standard for Web maps. Made popular by google since 2005, it has pros and cons and:
With any such projection, some distortion is unavoidable. In the Mercator projection, geographical features further from the equator are exaggerated in size. For example, Greenland appears to be of a similar size to Africa. However, Africa is actually more than 14 times as large (by area).
$ curl http://127.0.0.1:8000/tileMatrixSets | jq '.tileMatrixSets | .id' "CanadianNAD83_LCC" "EPSG3413" "EPSG6933" "EuropeanETRS89_LAEAQuad" "LINZAntarticaMapTilegrid" "NZTM2000" "NZTM2000Quad" "UPSAntarcticWGS84Quad" "UPSArcticWGS84Quad" "UTM31WGS84Quad" "WebMercatorQuad" "WorldCRS84Quad" "WorldMercatorWGS84Quad"
You can easily add more TileMatrixSet support, see custom tms.