It may not be the most striking or impressive of images, but the most viewed photograph of all time is probably "Bliss" - a photograph by Charles O’Rear which was set as Microsoft Windows XP's default wallpaper for the "Luna" theme and is estimated to have been seen by an audience of 1 billion.
The photograph was taken by O'Rear (a former National Geographic photographer) while on a break from another assignment in California’s Napa Valley and was originally published back in 2002. O'Rear hasn't ever disclosed what Microsoft paid him for the rights to the image, but he has said it's an "extraordinary" amount.
Speaking to blog Mashable about the image, O'Rear said: "All the folks I talk with agree it is the most 'recognizable' photo ever. If it were shown to a villager in rural China, for example, good chance they would recognize it. If it were shown to astronauts on the ISS, good bet they would know it, too. I have seen it appear in photos of the White House situation room, the Kremlin, etc."
Image copyright: Microsoft