is the information, held within an image file, about the camera that took the image, the settings used, and numerous other items of data about that image. then, is data about data.
Many photographers will also know it as the EXIF, although there other names for this data including IPTC and XMP. The main reason for so many names is camera manufacturers developing different ways of storing it in the earlier days of the digital revolution.
The point of this article though, is not to sort out the How, Who and Where, but more to help explain the Why, What and When!
Why should we know about?
On it's own, this information is useful from the photographers point of view, especially in their early days in the craft, but is not an essential to the more experienced cameraman. On more advanced, professional cameras though, there is the ability to input, through the camera firmware, such details as copyright information, and that starts to become a lot more useful.
Modern cataloging software has the ability to insert this kind of information if your camera doesn't have the ability, and it is the first bit of information that should be added to every image you take. If only for this reason alone, you should always import your images to your computer hard drive rather than simply copying or moving from the flash card.
At this point you should explore the other metadata fields that can be filled in by the Photographer. (The data can be found under 'File> File Info' in Photoshop) They include "Title" "Description" "Keywords" as well as such things as contact details, copyright url and a number of others. By filling these fields in you give your image a unique identity that can indicate to anyone looking at your file who took it and what it shows.
That information is then available to seach engines designed to read the metadata. That can include systems on your own computer, which helps you find the image when you want it, as well as any image libraries that you may submit your images to, and, through their search engines, potential clients!
Those clients can then contact you directly should they want to know, for instance, if you have a variant (you do shoot variants, don't you?) such as a different angle or orientation. they will also have a link to your website where they might find other images they like without the competition of other photographers in the original library.
When should we use Metadata?
The short answer to this is all of the time. Get into the habit of captioning and keywording every image as soon as you import it onto your hard drive. It's all to easy to leave it and either forget about it, miss it or simply get such a build-up of files that it is simply too gutty a job to ever try and catch up on!
And once the data is in there, leave it there! Never use the 'save for web' abilities of manipulation progams, as this helps compress file sizes by stripping out that data. After all the trouble you took getting the image, processing it, keywording it and inserting your copyright information, why strip it out at the last minute before showing the image to the world? Folks who use 'save for web' and then whinge about their images being stolen are, quite simply, asking for trouble. So it is better that your image takes a second longer to load than becoming an 'Orphan Work' that has no 'easily identifiable' owner of the copyright.
In summary, metadata will work for you for years to come by helping both you and others to find your images and identify them for what they are and who they belong to. It is in your own interest to use it in every image you take!
For more info see Useful Links