What is meaning of hmm in chat?

"Hmm" is an expression used in chat to indicate that the individual is pondering or considering something. It is typically conveyed as a neutral or contemplative response, and is often used when the individual is unsure of how to respond or is contemplating their response. It can also be used to indicate skepticism or doubt. In short, "hmm" is an expression used to convey thoughtfulness, contemplation, and uncertainty.