With high-capacity memory cards being so cheap, it's very easy to come home from a simple day out with the kids with fifty or sixty photos in your camera, and a two-week holiday can easily generate several hundred snaps. If you're a keen photographer who's had a digital camera for a couple of years, by now you've probably got several thousand photos lying around on your hard drive, probably scattered around dozens of confusingly labelled folders. Unless you keep your collection well organised, finding any particular photo can be a nightmare. Some people keep photos in named folders, with a folder for each theme, but what if a photo fits into more than one theme? Some people prefer to sort their photos by date, and indeed some photo handling programs do this by default, but that doesn't help you to find photos on a particular theme or featuring a particular person.
The best way to organise your photo collection is by using keywords. Keywords are a common concept in computerised searching. They are a series of single words or brief phrases that describe the contents of a document or image. They are attached as labels to the files, and are normally only seen by the computer on which the data is stored. For example, the huge database of articles on the TrustedReviews website is organised using keywords, which are invisible to the user. When we write an article, part of the software that runs the site allows us to attach keyword labels to it to help with searching, such as "tutorial, photoshop, bridge, keyword, organise" etcetera. If you type the word "tutorial" into the search window above, the computer running the site quickly locates every article with that label and displays its results as a list.
Similarly your digital photos, which are stored as digital data files both in your camera and on your computer, contain more information than just the picture itself. Information about the date and time the picture was taken, the dimensions of the image, the type of camera and the camera settings used to take it, and the thumbnail image displayed on your camera's monitor are all stored along with the image data in what is called the EXIF (Exchangeable image file format) file format, although it is also often referred to as metadata. Using an image editing program you can usually alter or add to some sections of this data, and your additions are then also stored along with the photo.
There are several different types of user-editable metadata, including copyright information, GPS co-ordinates and of course keywords. If you use Windows Vista you can edit the metadata directly through folder options, but it's usually better to do it using an image editing and sorting program, such as Adobe Bridge, the file browser program which is installed along with recent versions of Photoshop. You can also edit keywords using the free Google image handling program Picasa, although here they're called Tags. You'll find them in the File menu.