Common cold

The common cold or rhinovirus describes a number of strains of a small very contagious RNA based virus. Next to ameobic dysentery and dental caries (cavities), it's the most commonly suffered disease in the world. However, it's never fatal and will resolve itself of its own accord within 7-10 days after symptoms appear.
It's usually contracted when in contact with the virus and then subsequent (usually frequent) touching of one's face and eyes.
Although patients become immune to the strain of the cold they're exposed to once they recover, there are literally hundreds of strains of the common cold, each one of which has a unique protein coat. As such, ironically, older patients are much less likely to get colds than younger ones.
Although the common cold virus thrives in the nasal cavities, it cannot survive normal body temperature. The nasal cavities are slightly cooler. However, when the nose is congested, the temperature of the nasal cavities become closer to body temperature.
Prevention is the best course, and handwashing is probably the best preventative measure against infection. However, once infected, patients should get as much rest as possible and drink plenty of fluids. Symptoms should be treated, but aspirin should be avoided for children due to the risk of Reye's syndrome, although Reye's only affects patients infected with influenza.