This chapter explains what a PhD is and is not. A PhD is an apprenticeship in creating new knowledge: learning to frame meaningful questions, pursue them systematically, and defend conclusions under expert scrutiny. It outlines the typical structure of doctoral study and how it varies across regions, then describes common forms of contribution in AI, from methods and theory to evaluation and problem framing. The chapter also addresses the human side of the process and why persistence and judgment matter more than perfection.