The term "brain drain" dominates popular discourse on high-skilled migration, and for this reason, we use it in this article. However, as Harry Johnson noted, it is a loaded phrase implying serious loss. It is far from clear that such a loss actually occurs in practice; indeed, there is an increasing recognition of the possible benefits that skilled migration can offer both for migrants and for sending countries. This paper builds upon a recent wave of empirical research to answer eight key questions underlying much of the brain drain debate: 1) What is brain drain? 2) Why should economists care about it? 3) Is brain drain increasing? 4) Is there a positive relationship between skilled and unskilled migration? 5) What makes brain drain more likely? 6) Does brain gain exist? 7) Do high-skilled workers remit, invest, and share knowledge back home? 8) What do we know about the fiscal and production externalities of brain drain?