In psychology, an impression is the event when one person first encounters another person and forms a mental image of that person. Impression accuracy varies depending on the observer and the target (person, object, scene, etc.) being observed. These impressions can be nearly impossible to reverse or undo, making those encounters extremely important, for they set the tone for all the relationships that follows. So, whether they are in your career or social life, it's important to know how to create an impression.