The lung is a highly complex organ that can only be understood by integrating the many aspects of its structure. There is increasing interest in defining childhood asthma phenotypes, following decades of research into understanding mechanisms of asthma development and their genetic background without significant breakthroughs. Despite the medical profession's best efforts to define asthma, identify risk factors and natural development of asthma in birth cohorts, and find characteristics that distinguish one type of asthma from another, we still do not know the relevant characteristics of the various subgroups of childhood asthma. This review will briefly describe the importance of identifying childhood asthma phenotypes, the observable characteristics of the disease, and the previous and current approaches used to find them.