Originally posted by micromacro Ok, plain English please
So, google finds random images, and if it puts in own search, PF applies logo, right?
Google creates an index of every page on this site. It knows what images are hosted here and can gather information about that image from the Exif data in that image. That can include focal length, shutter speed, ISO etc. It can also include Geolocation data if the camera has a GPS.
Some applications strip Exif from a file when you export a JPEG. Lightroom can strip that data, but does not by default. But as this is a photography related site it helps to keep that data intact.
You can also lose Exif by posting a photo larger than the maximum allowable size. If the site has to resize it it strips the Exif. But it is much better to resize the image yourself, the site tends to make it crap.