You can add objects to the map to designate points, lines, areas, or collections
of objects. The 3D Maps in Maps JavaScript API calls these objects overlays. Overlays are
tied to geographic coordinates, so they move when you drag or zoom the
map.

## Overlay types

The 3D Maps in Maps JavaScript API supports several different types of overlays that you
can add programmatically:

- A **[popover](https://developers.google.com/maps/documentation/javascript/3d/popovers.md.txt)** is a special kind of overlay for displaying content (usually text or images) at a given location on a map. Popovers are analogous to [Info windows](https://developers.google.com/maps/documentation/javascript/infowindows.md.txt) in the Maps JavaScript API.
- Lines on the map are displayed using **[polylines](https://developers.google.com/maps/documentation/javascript/3d/shapes-lines.md.txt#polylines)**, represented as an ordered sequence of points connected by line segments.
- Areas of arbitrary shape on the map are displayed using **[polygons](https://developers.google.com/maps/documentation/javascript/3d/shapes-lines.md.txt#polygons)**. Like polylines, polygons are an ordered sequence of locations. Unlike polylines, polygons define a region which they enclose.
- **[Models](https://developers.google.com/maps/documentation/javascript/3d/models.md.txt)** are gLTF resources that are rendered on the map as 3D shapes.