Asthma and allergy share a similar and very close course, especially through childhood. Considerable research effort has been put in untangling these associations; however, it is now becoming obvious that this is an exceedingly difficult task. However, there are variants such as exercise-induced asthma, late-onset asthma, and some forms of occupational asthma are not typically associated with allergy. The current book covers the different aspects of the prevalence, risk factors and prevention, mechanisms, diagnosis, and treatment of asthma.