Asthma is the most common chronic disease in childhood, imposing a huge burden on the patient, their family and society. It is a worldwide disease with variable expression between countries and between different populations in a country. There is evidence that its prevalence has increased considerably over the last two decades and is still increasing, despite there being some indications that the increase in prevalence may have plateaued in some countries in the last few years. Better understanding of the natural course of asthma and improved asthma control can lead to a decreased burden on the patient, their family and society. The burden of asthma consists mainly of a decreased quality of life for the patient and their family, as well as high costs for society; the healthcare expenditures for asthma in developed countries are 1-2% of the total healthcare costs.