I tried searching on it, and found a few threads about materia becoming things, and things turning into materia, but I didn't really follow it.

I read another thread that started something like "...fans of FFVII will be excited about materia...", and went on to assume you just knew, more or less, what it was.

So for someone that (sadly) has 'no' FF experience at all (prior to this game), what is Materia?