Definition & Meaning of "hair of the dog"

What is the origin of the idiom "hair of the dog" and when to use it?

The idiom "hair of the dog" is often used in the context of drinking and refers to the belief that the best cure for a hangover is to have another alcoholic drink, typically the same type of alcohol that was consumed the night before. The origin of this expression comes from an old folk remedy, which suggested that a person who had consumed too much alcohol could alleviate their hangover symptoms by ingesting a small amount of the same alcoholic beverage the next day, likened to "a hair of the dog that bit you." While this remedy is not a recommended treatment for hangovers, the idiom remains in use today, often with a humorous or sarcastic tone.