Runny nose is excess drainage produced by nasal and adjacent tissues and blood vessels in the nose. This drainage may range from a clear fluid to thick mucus. Runny nose drainage may run out of your nose, down the back of your throat or both.
The terms "rhinorrhea" and "rhinitis" are often used to refer to a runny nose. Strictly speaking though, rhinorrhea refers to a thin, relatively clear nasal discharge. Rhinitis refers to inflammation of the nasal tissues from a number of causes, which usually results in a runny nose.
Nasal congestion may or may not accompany runny nose.