This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book aims to explain how to become qualified to practice in the area of professional psychology, right from school until being fully qualified. It hopes to provide an idea of how careers in the different areas of psychology can develop over time and how the profession of psychology might change as it continues to develop in the future. Psychology is still a relatively young profession compared to many long-established professions such as law, medicine, and accounting, however it has grown incredibly rapidly over the last few decades. The British Psychological Society (BPS) is the professional body and learned society for psychology in the United Kingdom. One of the first people to use the title "Psychologist" in a professional context was Lightner Witmer who established what is widely recognised as the world's first psychology clinic in 1896 in Pennsylvania.