What message is sent to an IM client to indicate that the other person in an IM conversation is writing something?

The message indicating that another person in an instant messaging (IM) conversation is writing something is commonly referred to as "isComposing." This term is part of the real-time messaging protocol and is used to notify users that the other participant is currently typing a message. This feature enhances the communication experience by letting users know that a response is being formulated, which can help manage expectations during conversation.

The term "isComposing" effectively communicates that ongoing interaction is taking place, allowing the other participant to see that their conversation partner is engaged. This is particularly useful for maintaining the flow of conversation, as it can prevent interruptions or overlapping messages.

Other terms like "Typing," "Message In Progress," or "Writing Now" might convey a similar idea in casual conversation, but "isComposing" is a standardized term utilized in various IM protocols and applications, making it the most accurate choice in this context.