“Coffee, black…” as Janeway has frequently requested. The job of creating coffee and millions of other food and items belongs to one thing: the replicator. The best way to describe a replicator would be a transporter with a different purpose. Just like a transporter stores genetic makeup in a data file, a replicator stores billions of molecules that can be arranged in practically any order, creating anything one could want. Best of all, the process can be reversed, so something like a dirty plate could be dematerialized and stored for later re-materialization into a clean one.
Everything created by the replicator is real, just like everything that is a collection of molecules today is real. The difference is the ability to customize according to the user’s liking. If you’re craving alfredo but don’t want all the calories, just ask – the replicator can easily create a zero-calorie alfredo dish just for you. If you always loved Shakspere but wanted illustrations too, just ask – it can create a wonderfully illustrated version of Hamlet. The possibilities are endless, but there is a certain limitation.
Due to the common science law that matter can neither be created nor destroyed, the replicator can’t “create” more atoms for re-materialization. So, there is a finite supply of molecules in Voyager’s replicators. Because some of the things replicated aren’t returned in their entirety, that supply could quickly run out. Hence the need for rations arose, especially because Voyager had such a long journey ahead of them. Rations became so valuable, they were like money – if you wanted something valuable, you’d have to sacrifice other things and save up. This is where objects like Harry’s clarinet came into play. So, as incredible as the invention is, it still has its draw-backs. Use it wisely.
I don’t know everything. I did a bit of research before creating this article. If you want a more extensive explanation, click here: http://en.memory-alpha.org/wiki/Replicator