Suspense can be defined in at least two ways. We can look at suspense as a state of mind created in the audience by a work of literature or film. We can also define suspense as a genre of literature and film.  

As a state of mind, suspense is characterized by anticipation. Suspense occurs when the audience is unsure of what will happen next in a story, when the audience is anticipating an upcoming event, or when an outcome is uncertain.

Suspense is a feeling of uncertainty and anxiety about the outcome of certain actions, most often referring to an audience's perceptions in a dramatic work.

As a genre term, suspense works are also often also known as "thrillers". The suspense, or thriller, genre can be broadly defined as consisting of works that feature suspense as a major element in the work. 

Thriller is a broad genre of literature, film, and televisionprogramming that uses suspense, tension and excitement as the main elements.

Some examples of the suspense genre include many of the works of Alfred Hitchcock and the novels of Michael Crichton.