What is the origin of the idiom "throw in the towel" and when to use it?

The idiom "throw in the towel" has its origins in the sport of boxing, where a fighter's coach or trainer would literally throw a towel into the boxing ring to signal their fighter's defeat and surrender, thereby ending the match. This practice usage back to the early 20th century. In a broader context, the phrase is now used figuratively to mean giving up or admitting defeat in the face of a challenging or difficult situation.