Definition & Meaning of "[add] fuel to the fire"

What is the origin of the idiom "add fuel to the fire" and when to use it?

The idiom "add fuel to the fire" is believed to have originated in the medieval era when people would use fire as a means of heating and cooking. The phrase is used to describe a situation where someone is making a bad situation worse by doing or saying something that exacerbates the problem. The idiom implies that the person is intensifying or increasing the severity of the problem or conflict.