Thanks largely to Google Earth, released by Google in 2005, finding information linked to geographical locations is becoming far easier. Now, earlier this month, Google unveiled new layers for Google Earth: collections of practical and educational resources related to specific places on the planet.

Almost any geospatial data can now be easily imported into Google Earth. This image shows the 3-D model of a building, developed using software from Bentley Systems, and placed within Google Earth. (Courtesy of Bentley Systems)

Icons linking to this mass of information--which is being provided by organizations such as the United Nations, the U.S. National Park Service, National Geographic, and Turn Here, a publisher of city guides--appear atop the Google Earth landscape with the click of a mouse.

Although details such as buildings, national boundaries, and road networks have long been a part of Google Earth, this new "featured content" material represents the website's first official attempt to build what might be described as a geographically indexed world encyclopedia.

In fact, with more than 100 million copies of Google Earth downloaded between June 2005 and March 2006 (and an undisclosed number since then), Google stands to dominate the online mapping industry.

"People don't know how much good geocoded information is out there. Google is trying to correct that," says Frank Taylor, a North Carolina-based entrepreneur who publishes Google Earth Blog, an unofficial guide to the program's features.

On its surface, so to speak, Google Earth is simply a collection of zoomable aerial and satellite photos carpeting a 3-D model of the Earth. But the software's real significance is much broader. Almost any type of information can be uploaded to the Web and then downloaded directly into Google Earth, as long as it is encoded in Google's open file format, KML, where it's visible as a new "layer," or annotation, superimposed on the satellite data. Today, thousands of individuals and companies are using KML to create and share their geotagged documents, turning Google Earth into a giant source for location-specific data.

With the new featured content, Google is calling attention to some of this information--from trail maps, professional nature photography, QuickTime movies, and links to magazine articles, to images from space documenting environmental degradation in various regions of the world over time. For example, the United Nations Environmental Program has provided 35 years of Landsat photos that can be overlaid on Google Earth, illustrating changes in "crisis zones" where human expansion and climate change are causing potentially irreversible damage to the natural environment.

"We wanted to put some of this content right inside the application, one click away," says John Hanke, Google's general manager for Google Earth and Google Maps. (Hanke's virtual-mapping company, Keyhole, was acquired by Google in 2004; KML stands for Keyhole Markup Language.) "Most of it was stuff people were already in the process of publishing in KML, and we just brought it in." Many government and nonprofit organizations are busy preparing and publishing information in KML, which is a simple variation of XML, the Web's main formatting language.