Wendy Pojmann wasn’t planning on writing an entire book about espresso. In fact, she was in Italy for something entirely different — researching the history of Italian women in the Cold War at the Central Archives of the State in Rome. That’s when she stumbled on a great idea.

“I was engaged in the conversation about espresso with the barista there, because a lot of times, as an American, you have to clarify whether you really want espresso or not,” Pojmann said. “We started talking about differences between American ways of drinking coffee and sort of dawned on me that I’m like, I should be writing a book about this.” So she did.