Vector Tile

When people say "vector tiles", they almost always mean tiles in a data format called Mapbox Vector Tiles or MVT. The Mapbox Vector Tile Specification defines this file format. Mapbox also offers a guide with visuals explaining how the format works.

At a high level, MVT tiles provide an efficient binary encoding for map features. Features have geometries (which can be points, lines, or polygons, similar to GeoJSON) and may also have attributes (key-value pairs, where keys are strings and values are strings, ints, floats, or booleans). MVT provides a compact binary encoding of this data, based on the Protobuf binary serialization format.