The inflammation of the bronchi is termed as bronchitis. Bronchi are the path connecting the trachea to lung. Bronchitis is mainly caused due to smoking and atmospheric pollution. At the beginning it starts with cough producing sputum. There are two types of bronchitis- acute or sudden onset and chronic or persistent bronchitis. Acute bronchitis is caused due to both viral as well as bacterial infections. This happens more during winter and it prevails for very short duration of time. Main suspects of this acute bronchitis are smokers, children, aged people etc… Chronic bronchitis affects people for longer time. This narrows down the air valve and widens the alveoli. Chronic bronchitis and emphysema are together known as COLD (Chronic Obstructive Lung Disease).