Zoom in several times using the <shift> and drag method.
Notice how the Back Arrow is highlighted while the Forward Arrow is grayed out.
The icon with the Back Arrow represents the Previous Extent Tool.
It is available for use if you want to go back to the previous extent.
The icon with the Forward Arrow represents the Next Extent Tool.
It is grayed out. Nothing will happen if you click on it.
Click once on the Previous Extent Tool.
The map zooms to the previous extent.
Notice, how the Next Extent Tool is no longer grayed out.
You can click on the Next Extent Tool to jump back to where you were before.
This Web Application keeps track of all your map extents as you zoom in and zoom out.
The Forward and Next Extent tools allows you to step through these stored extents.