A contagious viral infection of the lining of the nose, sinuses, throat, or lung airways. Colds are caused by more than 200 different viruses, known as rhinoviruses. These are not the same viruses that cause influenza .
Colds are very contagious.
The virus gets into the air when someone with a cold coughs or sneezes. The virus can also be spread when someone with a cold coughs or sneezes into their hand, then touches common objects such as the telephone receiver or doorknob. Children have more colds than adults. Children may have 10 colds a year, and adults may have 3 colds a year. After you have a cold, you become immune to the particular virus causing that cold.