Every encounter between two people begins with a greeting. Be it a quick `Hello!' or the somewhat longer and gracious `Sula manchwanta galunga omugobe!', shaking hands or shaking, well, rather more private parts of our anatomy, we have been doing it many times daily for thousands of years. It should really be the most straightforward thing in the world, but this apparently simple act is fraught with complications, leading to awkward misunderstandings and occasionally even outright violence. Why is that? Why are greetings so important? Can we ever find the perfect way of saying hello? In the illuminating and entertaining One Kiss or Two? Andy Scott - a well-travelled former diplomat, and no stranger to fumbled first contacts himself - goes down the rabbit hole to take a closer look at what greetings are all about and how they have developed, and discovers a kaleidoscopic world of etiquette, body-language, evolution, neuroscience, anthropology and history. Through in-depth research and his personal experiences, and with the help of experts ranging from the world-famous primatologist Jane Goodall to the UK's etiquette coach par excellence William Hanson, Scott takes us on a captivating journey through a subject far richer than we might have expected. By the end of it, we are able to make more sense of what lies behind greetings - and what it means to be human.