"Google Earth is an interactive mapping application that allows users to navigate (or "fly") the entire globe, viewing satellite imagery with overlays of roads, buildings, geographic features, and the like. Educators can use it to assess and bolster students' visual literacy. Students can use it to develop a context for spatial and cultural differences globally."
Source: Educause, 7 things You Should Know About Google Earth
Available in three versions:
Desktop
Full-featured access to Google Earth
Mobile
Google Earth in the palm of your hand
Check out the Google Earth YouTube Channel for video showing intermediate and advanced features of Google Earth:
- satellite world coverage
- 3D buildings
- terrain: mountains, valleys, below the sea
- map data
- historical imagery
Google Earth has a broad scope of coverage and dozens of features, for more help click Google Earth Help.