If you're reading this, then you probably have some interest in etymology, because it's the study of the sources, history, and derivations of words.
What "genealogy" is to a family or people, etymology is to words. A genealogist studies the history of a family: where they came from, how they got there, and what their history is. An "etymologist," or a person who studies etymology does the same thing with words. Etymology looks at the roots of words — for example, whether they started out as Latin, Greek or as some other language — and how they took on their current meaning. When I tell you that the -logy part of etymology almost always means "the study of," that is, in itself, etymology.