[You know, he shouldn't be surprised that he's finally found someone who's never heard of this at all - at the same time, this is literally the first time this has happened, and the kneejerk response of 'boy, do you live under a rock or something' is rather difficult to control.

But he'll make a valiant effort. Just for you!]

That depends on your definition of "elemental manipulation" - it's the practice of altering the form or structure of given materials. It has a rather wide range of uses - some are based around creation, such as healing, fixing things, or forming items or artifacts for specific uses; some, on the other hand, are based more around destruction, such as forming fire, manipulating the human body in all sorts of horrid ways, manipulating the energy in one's surroundings to force explosions out of just about anything. Most alchemists are capable of doing a bit of both, but they generally aim for one or the other.