Today we live in the information age. Wherever we look it surrounds us, and with the help of ever more efficient devices, from the internet through to mobile phones, we are producing, exchanging and harnessing more than ever before. But information does far more than define our modern age - at a fundamental level it defines the material world itself, for it is through its mediating role that we gain all our knowledge, and everything derives its function, existence and meaning from it. In twenty-five short chapters, von Baeyer takes us from the birth of the concept of information and its basic language, the bit, through to the coal-face of contemporary physics and beyond relativity; black holes; randomness; abstraction - explaining why it has the power to become the most fundamental concept in physics - as fundamental as mass and energy.