When you run the program, the red text paragraph appears in Immediate mode. What does it mean? The program encountered an exceptional case (i.e. division by zero) while running. You have errors (i.e. a missed bracket) in your statement(s) or program structure. The program doesn't do the right thing (i.e. ' 2+2=22 ). You used the wrong Python app (i.e. not IDLE) It's a glitch in the Python Online app (it happens, because it is not a real Python environment)