Sneezing is a sudden, forceful expulsion of air from the lungs through the nose and mouth. It is often triggered by irritants in the nasal passages, such as dust, pollen, or strong odors. The body uses sneezing as a reflex to clear these irritants and protect the respiratory system. During a sneeze, the body takes a deep breath, and the diaphragm contracts, pushing air out at high speed. This action can help remove particles and germs, making sneezing an important part of the body's defense mechanism against illness. Common causes of sneezing include allergies and respiratory infections like the common cold.