These theoretical differences partly reflect the complexity of the subject matter. Perhaps more importantly, there’s a very real sense in which we are all ‘Psychologists’ in our everyday lives: Psychologists as scientists/researchers use fundamental cognitive processes in order to investigate those same processes (such as perception and memory); hence, Psychologists (with an upper-case ‘P’) study human psychology (with a lower-case ‘p’), making the relationship between the discipline and the subject matter unique. However, there are important differences between the Psychologist-as-investigator and the person-as-‘Psychologist’. Also, the boundaries between Psychology and other subject disciplines aren’t clearly drawn, and what this chapter aims to do is make them sufficiently clear to enable you, the reader, who may be ‘visiting’ Psychology for the first time, to find your way around this book – and the subject – relatively easily.