type of camera used
settings used when pix was taken
time and date.
you can easily turn off gps settings on most camera's, but all of the other info is still there, and can easily be found out.. you can use any number of free online sources to delete all exif data, or if you have microsoft paint, and simply make a copy of a pix and save it through paint, it will also remove all exif data
if you ever look at some pix online, you will see stuff like 500x 600 .. blah blah blah, that's the exif data..