Viral??? As in Virus?  yes, Viral   comes from the medical term Virus. A Virus  , as everybody knows, is very quickly spread form person to person and this is precisely the meaning behind this expression. When we say that  a video, a picture, an email, a story… goes  viral , it becomes very popular, spreading very fast  on the Internet

For ex: “This video will go viral within minutes of its release”

One of the most successful viral videos was Susan Boyle’s performance in Britain’s Got Talent,viewed 100 million times in nine days.