📄️ Polygons with holes
The data layer is how you draw polygons. A polygon can have holes cut out of it, which a Polyline can't do.
📄️ Popups on features
There are three ways to show a popup for a feature in a data layer. Which one you want depends on whether the popup is the same for every feature.
📄️ The map's data layer is shared
Every map has one data layer of its own, which you get with map.data. Google gives each map exactly one, so everything that uses map.data is putting its features into the same place.
📄️ Tooltips on features
Tooltips work the same way as popups on a data layer, so Popups on data layer features covers most of what you need. This page is what's different.