Definition & Meaning of "long story"

What is the origin of the idiom "long story" and when to use it?

The idiom "long story" is an informal expression that has evolved over time to indicate a complex or time-consuming narrative. Its origin lies in the tendency of individuals to preface or follow up a detailed account with the phrase "long story" to warn listeners that the explanation may take a considerable amount of time. This idiom is a colloquial way of signaling that there is more information than can be conveniently conveyed in a brief or succinct manner.