Award-winning campaigner and writer Caroline Criado Perez shows us how, in a world largely built for and by men, we are systematically ignoring half the population. She exposes the gender data gap - a gap in our knowledge that is at the root of perpetual, systemic discrimination against women, and that has created a pervasive but invisible bias with a profound effect on women's lives. Caroline brings together for the first time an impressive range of case studies, stories and new research from across the world that illustrate the hidden ways in which women are excluded from the very building blocks of the world we live in, and the impact this has on their health and wellbeing.