Why do people cough?

Many reasons. Persons cough for various reasons. A cough can be associated with upper or lower respiratory infections, acid reflux, asthma (even without wheezing), post nasal drip, foreign body obstructions, lesions in the lungs such as cancer, and even damage to some nerves. There are many causes to a cough.
Reflex... Cough is a reflex designed to rid the airways of mucous containing bacteria, viruses, allergens, etc. By coughing, the body " cleans" the airways thus decreasing the possibility of infection. If secretions remain in the airways, they can become infected leading to acute bronchitis or pneumonia.

Related Questions

Why do people cough?

Reaction. Cough is a defense mechanism intended to clear the lungs and airways from anything offending them. Read more...

Why do people cough while eating. Many time and occasionally, which cause embrassment to go out to eat with?

GERD. Gastroesophageal reflux disease can certainly cause coughing while eating. Hiatal hernia can cause similar symptoms, as can various other gastric or esophageal diseases. You should see your doc for an evaluation and possible referral to a GI specialist. Read more...