Asthma is a chronic lung disease characterized by inflamed airways that constrict in response to triggers. It can be extrinsic, caused by allergies to things like pollen, or intrinsic, brought on by non-allergic factors like infections or stress. Symptoms include wheezing, coughing, and shortness of breath. Diagnosis involves pulmonary function tests and ruling out other conditions. Treatment focuses on avoiding triggers, using medications to open airways like bronchodilators and preventers like corticosteroids, and humidified oxygen during severe attacks to prevent complications like respiratory failure.