GoogleMap 是如何实现的？

Quoted from wikipedia:

Like other Google web applications, a large amount of JavaScript was used to create Google Maps. As the user drags the map, the grid squares are downloaded from the server and displayed to the user. When a user searches for a business, the location is pin-pointed with a red pin, which is actually a transparent PNG placed over the map. The technique of providing greater user-interactivity by performing asynchronous network requests with Javascript and XML has recently become known as Ajax. Specifically, Google Maps was built using the AjaXSLT framework.

The GIS (map) data used in Google Maps are provided by Tele Atlas and NAVTEQ, while the small patches of high-resolution satellite imagery are largely provided by DigitalGlobe and its QuickBird satellite, with some imagery also from government sources. The main global imagery base called NaturalVue was derived from Landsat 7 imagery by MDA Federal (formerly Earth Satellite Corporation). This global image base provide the essential foundation for the entire application.

The underlying technology used in both Google and Yahoo! maps is available from deCarta (formerly Telcontar)[2].

Amazing!