A cough is a protective reflex to clear your airways of mucus and irritants such as dust or smoke. It's rarely a sign of anything serious.
A dry cough means it's tickly and doesn't produce any sputum. A productive cough means sputum is produced and coughed-up to help clear the airways.
Most coughs clear up within three weeks and don't require any treatment. For more persistent coughs, it's a good idea to see your GP so they can investigate the cause.
Most coughs are caused by cold or flu. Other causes include:
Retrieved from: UK National Health Service, www.nhs.uk/conditions/cough/ (accessed 20 December 2017)