This is the story of how rum changed from a by-product of sugar-making into a global spirit shaped by trade, branding, law, production, and style. Along the way, it moves through the Caribbean, the Atlantic world, naval life, modern cocktails, legal definitions, and the often-misleading language of labels, before ending with a simple way to think about how different great rums can be. And to understand all of that, it helps to begin with what the sugar world first left behind.