Map tiles

The world is cut into a grid at every zoom level: at zoom 0 a single tile covers the whole planet, and each level splits every tile into four, so street level at zoom 18 has tens of billions of them. A tile is addressed by zoom, x and y (the {z}/{x}/{y} in a tile URL), and panning a map just requests the next few tiles, which browsers and CDNs cache well.

Raster tiles are ready-made images, usually 256 pixels square, simple to show but fixed in style. Vector tiles carry the raw shapes and labels, and the device draws them with WebGL, so the map can be restyled, rotated and kept sharp at any zoom, usually with smaller downloads. Tiles come from providers (Google, Mapbox, MapTiler, Stadia Maps) or can be generated from OpenStreetMap data and served from your own storage, for example as a single PMTiles file.