Google acquired Keyhole in 2004 to obtain the technology behind Google Earth.
Keyhole was a company specializing in geospatial visualization and satellite-imagery software. Google’s acquisition brought its technology into Google, where the product was developed and released as Google Earth in 2005.
The resulting application let users explore a virtual globe using satellite imagery, aerial photography, terrain data, and later three-dimensional buildings. It became a separate experience from Google Maps, although the two services share mapping and geographic data.
A frequent mix-up is with Where 2 Technologies, which Google acquired for mapping technology used in Google Maps. Keyhole was specifically associated with the virtual-globe software that became Google Earth. The original Keyhole product was called EarthViewer 3D.