Asthma is a chronic lung disease that causes narrowing of the airways. It was first described by Hippocrates in ancient Greece. Asthma symptoms vary between people and can be triggered by factors like allergens, air pollution, exercise and emotions. During an asthma attack, the airways become inflamed and narrowed due to muscle constriction and mucus production, making breathing difficult. Tests like spirometry and chest x-rays are used to diagnose asthma. Treatment focuses on preventing symptoms through medications and avoiding triggers.