Ably is introducing ephemeral messages to let developers deliver transient updates in real-time apps without polluting the system with unnecessary data. Ephemeral messages are only delivered to currently-connected clients and do not appear in message history, rewind buffers, or integrations like webhooks or queues, making them ideal for sending reactions, typing indicators, or cursor positions. By marking a message as ephemeral, developers can exempt it from storage, message history, and billing implications, saving on costs of retrieving messages from history. Ephemeral messages are available now in Ably Pub/Sub, and developers can quickly get started by following the provided documentation.