Definition & Meaning of "rain check"

What is the origin of the idiom "rain check" and when to use it?

The origin of the idiom "rain check" can be traced back to the late 19th century in the United States. It originated from the practice of issuing tickets known as "rain checks" during baseball games.When a baseball game was rained out or postponed due to bad weather, spectators would receive a rain check ticket that allowed them to attend a future game instead. It is often employed when unforeseen circumstances arise, conflicting schedules occur, or when someone is unable to attend an event or engage in an activity as initially planned.