BackgroundKnowledge of our immune system functions is critical for understanding allergic airway disease development as well as for selection of appropriate diagnostic and therapeutic options for patients with respiratory allergies.MethodsThis review explains the current understanding of the basic immunology of the upper airways and the pathophysiology of allergic responses, including the mechanisms behind allergic rhinitis.ResultsThe immune system can be divided to 2 main defense systems that function differently—innate immunity and adaptive immunity. Innate immunity includes several defensive mechanisms such as anatomic or physical barriers, physiological barriers, phagocytosis, and inflammation. The adaptive immune response is activated in an antigen‐specific way to provide for the elimination of antigen and induce lasting protection. Hypersensitivity reactions occur when an exaggerated adaptive immune response is activated. Allergic rhinitis is an example of a type I, immunoglobulin E, mediated hypersensitivity reaction.ConclusionToday we have several immunomodulatory treatment options for patients with allergic airway diseases, such as subcutaneous and sublingual immunotherapy. An understanding of the basics of our immune system and its method of functions is key for using these therapies appropriately.