How often have you wanted to store information about a file but had nowhere to put it? A caption for a picture, an original creation name for a document or a thumbnail JPEG for a large TIFF. Your options are to save multiple files or to store the filename and related information in a table in a database. This type of solution is fragile because the link between pieces is easily broken.
Now you can easily create file metadata and store it with the file. The information moves with the file and independent of the file name so you never need to worry about losing or mislaying it. It's invisible, blindingly fast and you can store any kind of information - text, images, binary data, XML - anything.