Darkside Economics is a book about a different use of economics – as a weapon to coerce other economies or to defend them from coercion. The topic is in the headlines today, but it has a long history of use and abuse. It includes sanctions, embargoes, tariffs, technology restrictions, financial tools and other new instruments. We look at the history of these practices, explain how they work and estimate their effects, from the point of view of aggressor countries, targets or small victims. The weapons often have negative economic effects, but these tools are now such a central part of both diplomatic and military strategy that they need to be understood better.