Viral phenomena are objects or patterns that are able to replicate themselves or convert other objects into copies of themselves when these objects are exposed to them.
Pokemon Go is a viral phenomenon by ABC 2 News - WMAR
They get their name from the way that viruses propagate.
A virus is a small infectious agent that replicates only inside the living cells of other organisms.
OfficeMax's Viral Phenomenon - Elf Yourself 2007 by officemax
This has become a common way to describe how thoughts, information, and trends move into and through a human population.
"Viral media" is a common term whose popularity has been fueled by the rapid rise of social network sites alongside declining advertising rates and an extremely fragmented audience for broadcast media.
Different from the "spreadable media", "viral media" uses viral metaphors of "infection" and "contamination", which means that audiences play as passive carriers rather than an active role to "spread" contents.
Memes are possibly the best-known example of informational viral patterns.
A meme, a neologism coined by Richard Dawkins, is "an idea, behavior, or style that spreads from person to person within a culture".