Here’s the first and most useful heuristic: user interfaces should always make visible the system status.
I really agree with this because when a system doesn’t show what it’s doing, I get confused or . I hate when I click something and I’m not sure if it worked, if I need to wait, or if something broke. Clear system status makes the experience way easier and reduces a lot of stress. It reminded me that even small UI choices affect whether users feel confident or lost when using something.