Nasal discharge refers to the fluid that comes from the nose, which can vary in color and consistency. It is often a sign of the body's response to irritants, infections, or allergies. Common causes include colds, sinus infections, and allergies, leading to symptoms like congestion and sneezing. The discharge can be clear, yellow, or green, depending on the underlying cause. Clear discharge is typically associated with allergies or viral infections, while colored discharge may indicate a bacterial infection. Monitoring the characteristics of nasal discharge can help in understanding the cause and determining if medical attention is needed.