Digital Asset Management is the fancy term for the way you store all your computer files. It deals with where you put files and how you find them. With a relatively small number of files, say under a few hundred, the way you store them doesn't matter much. You're never too far away from finding the file you're looking for. As your collection grows, having a good system becomes increasingly important if you want to be able to find anything.
With relatively small numbers, say under a few hundred, it's possible to get away with just dumping them wherever. As the number grows, the files become harder and harder to deal with unless you have a decent system for storage. For text based files, searching can help alleviate the need for . If you have lots and lots of photos, that's not a reasonable option.