Re: providing information about an image.
With digital images (and other digital sources) metadata - data about the data - can be used to describe relevant information, e.g. who created it, how, technical capture info, subject info, preservation, etc. This information sits along with the image itself. It's used widely in digital archiving, but I don't know how much other fields use it. And, of course, it depends on the honesty of the person supplying it.