When it comes to backgrounds that have appeared on a PC, then the one with the blue sky has to be the most famous of all. It is also seen as being the most widely used background. That is because it takes into an account of people loving it as well as being too lazy to change it to something that they may even prefer.
However, the photograph itself is taken from a real place and is not simply a computer-generated graphic. It was taken in 1996 and the location is in Sonoma County, California. It seems that their intention was never to create something that would, in its own right, become iconic as it was just an image to offer as an option when it came to the background. However, people took to it thanks to its brightness without being too in your face, and it was then able to hang around for a considerable period of time.