Coughing is a natural body reflex to get rid of any irritant or foreign matter that gets into the airway. When something irritates your throat or airway, your nervous system sends a signal to your brain. Your brain reacts by telling the muscles in your chest and abdomen to contract and expel a burst of air, that’s why a cough sometimes feels like a sudden explosion of air through your mouth.
While a cough can be irritating, it is an important defense mechanism that helps remove irritants like mucus, smoke, and allergens such as dust, mold, and pollen from our system. It is important to note that a cough is only a symptom, not a disease. Treating the underlying cause of your cough gives you the best chance of relief.

There are two main types of coughs, either:

To a trained ear, a cough can be distinguished by its sound. A dry, hacking cough sounds “hollow” without phlegm and tends to go into a long fit that keeps you awake at night. A chesty cough tend to make a “rattling” sound when you cough or even when you breathe due to the thickened phlegm in the throat and airway. Knowing the difference between a dry or chesty cough is important so that you can select the right treatment for your condition.

The main difference between a DRY and WET Cough is the amount of mucus production.

Mucus is a normal water secretion lining the airways. When you are healthy, the mucus is usually a thin, transparent, water-like gel. Mucus is required to trap irritants in the airway for the body to expel out.
If you have a common cold from a viral or bacteria infection, the infection can turn the healthy mucus into thickened phlegm that could be yellowish or green in colour.