Definition och Betydelse av "snowball effect"

What is the origin of the idiom "snowball effect" and when to use it?

The idiom "snowball effect" is derived from the literal concept of a snowball rolling down a hill, gradually picking up more snow and increasing in size as it goes. In a figurative sense, it is sued to signify a situation in which a small action or event triggers a chain reaction, causing an issue or situation to grow rapidly or become more significant.