It would be very simple just to say that D.A.S.MP is just a Module Player. It is not! Its main function is to play modules but even more the main goal is to make it the perfect module handler.
You can play the music modules with dozens of different players of which some are good and some are not. With very few of them can you maintain a list of your modules like you can with the D.A.S.MP (even more so with upcoming 4.0). So broader definition for it is one stop module solution. I am starting with the assumption that you are so called module collector not just module-per-week guy. If you just play one module every once and a while you will never find out what is best in D.A.S.MP and you might as well use one of those 13-in-a-dozen players hanging around. Note that this definition does not include DeliTracker II, which is propably the best of them but still doesn't have as versatile list handling as in D.A.S.MP.
With D.A.S.MP you can make whatever kind of module lists (list of modules which can be loaded to D.A.S.MP) you like. You can have one for maintaining a list of all your modules, some for regularly played modules, some for different type of modules... Usage variations are endless and since D.A.S.MP has so versatile list handling system you don't necessarily make different list, you might have one list and that is all. To give you an example: I have list containing about 4000 modules which I mostly keep in disks which I have about 300 hundred. Now normally finding one particular module or modules of certain style(s) or author(s) would be hard thing to do. Not with D.A.S.MP. With two mouse clicks you can make the D.A.S.MP to show you the modules of certain style(s) or author(s) or any combinations of these.
As mentioned above it is possible to give modules an author and a style, but it doesn't end here not even close. Furthermore you can give module a rating and automatically you get durations, module type, channels used and that sort of things. All these attributes help you manage your modules the most effective way ever.
Note that above I mentioned about 2% of features in D.A.S.MP so.. In pre-4.0 versions there were several options disabled in unregistered version which I now think was a big mistake. Therefore there is no feature limitations in upcoming 4.0 version, so have fun.
Signed: Pauli Porkka