A keyhole is a small opening in a door or lock that allows a key to be inserted for unlocking. It is typically shaped like a narrow slot or oval, designed to fit the specific shape of a key. Keyholes are commonly found in residential and commercial doors, providing security and privacy. In addition to their practical use, keyholes have also become symbolic in literature and art, representing secrets or hidden knowledge. The act of peering through a keyhole can evoke curiosity, suggesting that there is more to discover beyond what is visible, much like the themes explored in works by Edgar Allan Poe or Lewis Carroll.