Smoking is the inhalation of the smoke of burning tobacco encased in cigarettes, pipes, and cigars. Casual smoking is the act of smoking only occasionally, usually in a social situation or to relieve stress. A smoking habit is a physical addiction to tobacco products. Many health experts now regard habitual smoking as a psychological addiction, too, and one with serious health consequences. We proved the missions worked by performing a rigorous scientific experiment. As far as we know, this is the first ever randomised control trial run entirely within an app. Its success means we want to run many more and our goal is to constantly make our app more effective This is all entirely voluntary and you can download the app without taking part in the experiment. Your data will be kept anonymous and you can delete it at any time.