Action painting is a style of painting in which paint is spontaneously dribbled, splashed, or smeared onto the canvas, rather than being carefully applied. The purpose of action painting is to emphasize the physical act of painting rather than the end result. The resulting painting is supposed to make the observer think about the process of painting and the thoughts and emotions of the artist was feeling as he/she was creating the painting.
Jackson Pollock is well known for action painting. I have attached a website where you can view some of his paintings. You can also do a Google Image search for sample paintings.