The document discusses cough and its potential causes. Cough can be initiated by airway irritants, inflammation, or compression/constriction of the airways. Common causes of cough include infections, asthma, tumors, granulomas, congestive heart failure, and use of ACE inhibitors. The cough reflex involves both sensory afferent pathways and motor efferent pathways. Evaluation of cough involves considering its chronicity, associated symptoms, seasonality, relationship to postnasal drip or reflux, presence of fever or sputum, and underlying diseases or risk factors of the patient. Diagnostic tests may include imaging, pulmonary function tests, and sputum examination.