Human action recognition,Important area of computer vision research, an automated detection of events performed by humans from video data.An important task of low level video analysis is to extract useful information from a video sequence This book describes a novel feature for apturing information in a spatio-temporal volume based on regularity flow, what it is, how it works, and the benefits of using it for action recognition. The regularity flow describes the direction of least intensity change within a spatio-temporal volume. Our feature consists of weighted histograms of the computed regularity flow around selected interest points. We then apply this new feature to recognizing actions with experiments on known benchmark dataset.