not so sure about these but i think dll's help you extend your programming by adding extra functions, as for memblocks, they set asside memory blocks in your computer for storing and manipulating all sorts of data, i use them to store large number of bitmaps so i don't have to load from scratch in-game, instead just retrieve from the memblocks, i'm sure other people have their other uses for these.
your birth was a blessing, sent to live and die on earth as a lesson, we each have a star all you have to do is find it, once you do, everyone who sees it will be blinded - DMX