A MultiPolygon is a geometry type that represents multiple Polygons at once.
In GeoJSON, a MultiPolygon looks like this:
{
"type": "Feature",
"properties": { "name": "Square" },
"geometry": {
"type": "Polygon",
"coordinates": [[
[0, 0], [1, 0], [1, 1], [0, 1], [0, 0]
]]
}
}