WebMD describes the common cold as a group of symptoms in the upper respiratory tract. The symptoms are often caused by a large number of different viruses, up to 200, although the most frequent cause is the rhinovirus. Colds are contracted when the cold virus enters your body through the nose or mouth, and are easily spread when you touch someone else or common objects such as doorknobs.

The links below contain important information about how to prevent and treat the common cold.