This book aims to systemically summarize the key findings about Innate lymphoid cells (ILCs) and present the consensus of current views and prospective. ILCs are a class of newly recognized immune cells which play an instructive role in shaping immunity in physiological and pathological conditions. This book discusses the differentiation of ILC, the relation of ILCs with respiratory function, inflammation in the gut, skin disorders, cancer, neurobiology and microbes. The knowledge included in this book is valuable for both basic immunologists and clinicians in understanding the heterogenetic immune responses in disease and health.