This chapter discusses the key role and challenges of using classifications in science and professional fields. Classifications help us understand the world, but they also have drawbacks. The chapter acknowledges how the human brain naturally employs classifications as mental shortcuts (heuristics) for efficiency, but these same mechanisms can sometimes result in biases. Through examples ranging from natural classifications (like dangerous animals) to social and professional role categorisations, this chapter illustrates how classifications inform decisions and actions. The chapter critically examines how some classifications, particularly in social sciences and professional environments, can inadvertently promote division and discrimination rather than understanding and accommodation. Special attention is given to the misuse of classifications in professional contexts, including leadership and management domains, where false comparisons and the delusion of mutually exclusive values can emerge. The chapter concludes by emphasising that while classifications are necessary tools for understanding and organising our world, they must be used thoughtfully and with an awareness of their limitations to avoid reinforcing stereotypes or creating artificial divisions in professional practice.