If you shoot lots of digital pictures, learn how to take advantage of information called metadata to keep track of extra details. Image metadata is nonpicture information that’s captured and stored within a picture file. Most digital cameras use the Exchangeable Image File (EXIF) format to store metadata when saving pictures; images may also include metadata that conforms to the International Press Telecommunications Council (IPTC) and Adobe’s Extensible Metadata Platform (XMP) standards. (To learn more about the EXIF standard, visit http://www.exif.org; for more details about XMP, see http://www.adobe.com/products/xmp/overview.html.)
EXIF metadata typically includes the date and time the picture was taken, the width and height of the image (in pixels), the resolution (in dpi), and the color depth. Depending on the camera you use, metadata can also include technical information such as the camera model, flash mode, aperture, and exposure time. Some high-end devices even allow you to add audio annotations to images and store them in the same file.
A few bits of metadata are available in the ScreenTip that appears when you pause the mouse pointer over an image file.
Windows XP doesn’t allow you to edit image metadata. But you can use it to sort and organize image files in Windows Explorer. To see all available metadata for an individual image file, right-click the file icon and then choose Properties. On the Summary tab, click Advanced to display a scrolling list of available metadata properties and values. Image data appears above the Description data, as shown here.
To really take advantage of metadata, you need to customize the Windows Explorer window so that metadata information is visible. To do so, switch to Details view, right-click any column heading, and then select the names of available fields to make those columns visible. Click More at the bottom of the list to see all possible fields. If you add the Date Picture Taken column, for instance, you can then click the column heading to sort by this field and gather pictures that were taken around the same time.
[Note: This tip is adapted from Windows XP Inside Out, Second Edition.]
Ed Bott 
Thanks. For a while I thought we weren’t going to get a tip of the day today. 🙂
Is there somehwere a reference which exif fields XP pulls the information out? I can edit some meta-data fields in Adobe Elements, but this doesn’t influence what I see on the explorer. I also tried out one of the exif editors available (exifer), and they’re easy enough to use, but again, there are so many exif fields available. some of them with really cryptic names. Is there somewhere a list which fields XP pulls in under which name?
Can anyone let me know any OpenSource API for adding my own custom properties to any of the files?