What is Google Earth?
Google Earth is currently available for download as a desktop application, although you need to be connected to the Internet to use it. Every time you open Google Earth, it automatically connects to Google's servers, giving you access to terabytes of geographical, political and social data. For instance, you can view a city with certain "layers" turned on, including topographical information, population data and crime statistics for the area. The layers and all of the map navigation buttons, including zoom, tilt and rotate, are all located in the Google Earth frame.

Launch page with toolbars

The big deal right now is that the basic version of Google Earth is completely free, and there aren't even any ads. Of course, this could change in the future -- as of October 2005, Google Earth is still in beta testing. So let's all start by downloading the free version of the software located at Earth.Google.com while it's still free and unfettered by ads. If your computer runs Windows (sorry, no Mac support yet) and is fewer than five years old, you should have no problem meeting the system requirements. If your computer can't run the application, read on to find out what you'll be able to do once you update your equipment.

Once you open Google Earth and start moving around a bit, you'll immediately notice one of the biggest "whoa" aspects of the program: Some of the information is 3-D, and the stuff that isn't 3-D is still a photograph -- there are no illustrated maps here. The baseline visual data comes from satellite imagery and aerial photographs taken by aircraft.

While Google Earth comprises an array of features that would probably take months to fully utilize, the basic features fit loosely into the following categories:

Local search
We'll address each of these utilities in the following sections. But first, let's find out where Google Earth gets its data.

Source: How Google Earth Works (how stuff works)

This is a great article covering the bases of Google Earth. It goes into the thick of the program showing you how to get the most out of it. I learned a few things about google earth, and hope you do too.