Because some new gadgets (Iphone and other newage smartphones) save all kind of data in a picture. Even the location where the picture was taken (coordinates)!
So next time you post a picture on Internet, ask yourself, can the info it contains harm me in any way? Predators must be angry now. But so is the Police (Yes, they are checking this too).
Windows users can try the Exif Farm found here. Its use is pretty straightforward.
See bellow how it displays the info:
Ubuntu users can use the command line tool called jhead, which is also a great tool to manipulate exif data (delete/change).
Get it by running this in terminal:
sudo apt-get install jhead
To delete all EXIF info from a picture run this:
jhead -purejpg /path/to/image.jpg
To delete all EXIF info from all pictures (jpeg) in current directory, run this:
ls | xargs jhead -purejpg
Alternatively, you could also try Exif, get it with:
sudo apt-get install exifAnd then check the manual with:
Another alternative to see EXIF data is this website, try it out if you hate installs.