Viral phenomena are objects or phenomena able to reproduce themselves self or convert other objects into copies of themself when other objects are exposed to it.

The concept of something, other than a biological virus being viral came into vogue just after the Internet became widely popular in the mid to late 1990's. An object, even a non-material object, is considered to be viral when it has the ability to spread copies of itself or change other similar objects to become more like itself when those objects are simply exposed to the viral object. While the concept definitely, (and originally), applies to biological viri (viruses) it is more commonly used to describe mostly how thoughts, information and trends move though and into a human population.