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

The origin of the phrase "long face" can be traced back to the early 19th century. The term "long" has long been associated with a sense of sadness or melancholy in various idiomatic expressions. It is commonly employed in everyday conversations, informal interactions, and literature to depict a visible expression of sorrow or dejection. This phrase is often used when discussing or observing someone's emotional state, particularly when they are visibly downcast or lacking enthusiasm.