This chapter maps the conceptual landscape surrounding happiness, clarifying how it overlaps with and differs from neighboring ideas such as various forms of well-being, flourishing, meaning, fulfillment, and quality of life. It begins by tracing everyday and disciplinary slippage among terms like happiness, subjective well-being, and life satisfaction, and then unpacks the “well-being family” (mental, emotional, psychological, subjective, affective, and cognitive well-being). Flourishing, thriving, and wellness are treated as broad integrative ideals, while the good life, life satisfaction, and fulfillment are framed as distinct ways of evaluating a life. The chapter then examines meaning, purpose, and mattering; dispositional orientations toward positivity; experiential patterns such as flow and psychologically rich lives; and population-level constructs including quality of life, welfare, livability, and happy life expectancy. Throughout, it distinguishes subjective and objective indicators of a good life and shows why terminological precision matters for research and practice. The chapter concludes by offering a working definition of happiness as the felt and evaluated quality of a life as lived from the first-person perspective, positioned within this wider concept family.