description: '**NB: Usage of this event is discouraged in favour of the** [receipts module](/client-server-api/#receipts). **Most clients will not recognise this event.** Feedback events are events sent to acknowledge a message in some way. There are two supported acknowledgements:`delivered` (sent when the event has been received) and `read` (sent when the event has been observed by the end-user). The `target_event_id` should reference the `m.room.message` event being acknowledged.'