Polygons

A polygon is a 2D shape (most of the time) in Google Earth. The icon for a polygon looks like this:

1. Click on the polygon tool - You see a familiar dialogue box:

Similar to the Placemark and Path tools, we can add a title and a description, and see some additional information about the polygon here. One of the most useful things that you can do is change the color and width of the border and color and opacity of the fill, in the second tab:

2. To create a polygon, simply start left clicking around - Left click to add points, and right click to remove points.

3. Change polygon line and fill color in the 'Style, Color' tab - You can change many properties of a polygon, including the opacity. 

One neat thing that you can do with polygons is give it a 3D look. This is done by going to the 'Altitude' tab, and then changing the mode to 'relative' and then putting in a value. The 'Extend sides to ground' option will change the polygon from a floating plane to a box, of sorts.