What is the origin of the idiom "on the edge of one's seat" and when to use it?

The origin of the phrase "on the edge of one's seat" is not definitively known, but it is believed to have emerged in the early 20th century. The expression likely originated from the physical posture of someone who is highly engaged or excited, leaning forward and perched on the edge of their seat. It is often employed when discussing thrilling or suspenseful experiences, such as watching a suspense movie, attending a live performance, or following a gripping sports event.