What is a "Spot the Difference" puzzle?

The object of a "spot the difference" puzzle is to identify the number of differences between two images that are almost identical. The images are often drawings, photographs or computer graphics, with certain details slightly amended or removed.

The number of differences between the two presented images may vary, but the principle is the same: the player must find where the two images differ. These types of games are also known as photo hunt games, and they are often found in children's puzzle and activity books. They may also be published in newspapers, with the answers listed elsewhere in the publication.