Suspence is the feeling of uncertainty and anxiety about the outcome of specific actions mostly directly linked to peoples perceptions whilst watching some kind of dramatic work. It is unsually assosiated with "heavy breathing", victims, darkness, pauses and tense music.
It is a viceral effect, that tends to leave people on the edge of their seats, feeling jumpy, heart beating fast, big eyes, and screams.
The audience tend to know more than the actors on the screen, and the scene begins with sense of normality and then lets the sinister element enter.