TerraServer-USA is a free online repository of public domain aerial imagery and satellite imagery, formerly known as Microsoft TerraServer. Though it was online as early as December 1997, the site was formally unveiled June 24, 1998 as part of an 18-month agreement between Microsoft, Compaq, and Aerial Images of Raleigh, North Carolina. Interestingly it was created as a demonstration system to advertise the scalability of Microsoft's Windows NT Server and SQL Server, and used images from the United States Geological Survey (USGS) and Sovinformsputnik (the Russian Federal Space Agency).

In January 2000, Microsoft and Aerial Images split their operations, creating two parallel Terraserver sites. The dualism still causes confusion among web surfers to this day. Microsoft wanted to stick with their free demonstration system, while Aerial Images wanted to press forward and use its marketing rights to Russian satellite imagery. Thus the Microsoft product became known as Microsoft TerraServer and more recently TerraServer-USA, while the Aerial Images company remained known simply as TerraServer. Microsoft stuck with USGS aerial imagery, while Aerial Images hosted the SPIN-2 and GeoEye satellite data. As a result, Microsoft lost virtually all of its foreign imagery.

The TerraServer name is a play on words, with 'Terra' referring to the 'earth' or 'land' and also to the terabytes of images stored on the site.

At present, the site claims to have black and white aerial photographs of approximately 97% of the United States. In 2000, the USGS launched the new Urban Areas program, which will ultimately take high-resolution color aerial photographs of about 100 major American cities. TerraServer has added Urban Areas data for 40 cities.

One consistent joke about the service is its depiction of the headquarters of Apple Inc. as barren land, using photographs taken in 1991.