Nowadays every photo taken with a mobile phone or digital camera contains metadata. This metadata, called Exif data, contains information about your camera, like brand and model name, the dimensions of the image and - when available - also GPS coordinates which reveal the location where the picture was taken.
File NameExample Ibiza.JPG
Creation Date2011-09-04 12:51:11
File Size234,015 bytes (228.5 KB)
Dimensions1024 x 765 pixels
GPS Coordinates 38.90983, 1.43867