The event feed is a running list of all that's going on within an operation. However, you're also able to add your own messages to the event log as a basic form of chat or generic information storage while operating. If Mythic has an error, these will be recorded in the event log with a red background and a button to allow "resolution" of the problem. If you resolve the problem, then the background will change to green. You can also delete and edit messages as needed: