Definition & Meaning of "a snowball's chance in hell"

What is the origin of the idiom "a snowball's chance in hell" and when to use it?

The phrase "a snowball's chance in hell" is an idiom used to describe a situation where something has virtually no chance of success or survival. The origin of this phrase can be traced back to the idea that a snowball would quickly melt in the extreme heat of hell, emphasizing the extreme improbability of success in unfavorable circumstances.