What is metaethics?

Metaethics is a field of philosophy that is frequently characterized as being concerned with the nature of morality at large. A more substantial description of the field is that it aims to explain (i) what the content of moral thought and talk is really about, as well as (ii) how this thought and talk relates to reality. For example, questions related to (i) might look something like the following: What do we really mean when we say things like ‘murder is wrong’ or ‘Hitler is evil’? When we make such claims are we purporting to describe the world, or are we fulfilling some other function, such as expressing our emotional attitudes towards the matter in question?  Regarding (ii), philosophers might ask something like: Are there objective moral facts about moral issues, such as e.g. about whether murder is wrong? If indeed there are, how do we get to know these facts? This is just a small sample of the kind of questions that the field of metaethics deals with. All such questions typically have to do with the metaphysics, epistemology, and semantics of morality.