This is a book about what numbers are and where they come from, as understood through their materiality, the material devices used to represent and manipulate them: things like fingers, tallies, tokens, and symbolic notations. This book is concerned with the natural or counting numbers – the sequence one, two, three, four, and so on, and maybe as high as ten or twenty or hundred – that are the basis of arithmetic and mathematics. While the book focuses on how concepts of number emerge and ultimately become elaborated as arithmetic and mathematics through the use of material devices, it will also examine related phenomena, like the way numbers vary cross-culturally.