What does it mean for a program to do something silently?
We say a program has failed silently, crashed silently, or silently done something if it has done it without displaying a message to the user, such as an error dialog, a success message dialog, or printed something on the terminal.
Doing things silently is a usability bug. Silent failures prevent users from troubleshooting the software they use, and succeeding silently makes them uncertain if they actually clicked the button or not inducing them to press the same button two times since they got not response the first time, which could be a potentially destructive operation.