What is thriller?

The thriller is a broad genre of literature, film, and television. It includes numerous, often overlapping sub-genres.

Thrillers are characterized by fast pacing, frequent action, and resourceful heroes who must thwart the plans of more-powerful and better-equipped villains. Literary devices such as suspense, red herrings, and cliffhangers are used extensively.

http://en.wikipedia.org/wiki/Thriller_%28genre%29