This article talks about the "visibility of system status" heuristic, which says "the system should always keep users informed about what is going on, through appropriate feedback within reasonable time." This is the first of 10 usability heuristics created by Jacob Nielsen.

"Definition: The visibility of system status refers to how well the state of the system is conveyed to its users. Ideally, systems should always keep users informed about what is going on, through appropriate feedback within reasonable time."

Summary of this article: "Communicating the current state allows users to feel in control of the system, take appropriate actions to reach their goal, and ultimately trust the brand."