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 St Petersburg.JPG
Creation Date2012-02-04 15:06:00
File Size137,809 bytes (134.6 KB)
Dimensions1024 x 768 pixels
GPS Coordinates 59.94217, 30.30683