Identify whether the activities are associated with positive externalities (external benefits), negative externalities (external costs), or no externalities. Obtaining an education results in externalities Overfishing results in externalities. Playing an addictive single-player cell phone game such as Happy Fish results in externalities. Reducing pollution results in externalities. Receiving a flu vaccine results in externalities. Enhancing the aesthetic appeal of a property in a residential neighborhood results in externalities. Developing a productivity-enhancing technology results in externalities. Cigarette smoking in a non-smoking section results in externalities. Eating a delicious cookie results in externalities.