This chapter discusses concepts of inequality and inequity in relation to health both within and between nations. It explores inequalities in health by characteristics, such as social class, gender, ethnicity, and the intersection of these. The chapter discusses the importance of the social gradient of health. It addresses competing explanations for health and social inequalities globally, including poverty and material deprivation, psychosocial factors, discrimination, and structural determinants of health. The ‘social gradient in health’ expresses the idea that health status is often patterned and that each successive increment in social position confers additional advantage. The way in which inequalities are measured, and the ethical priorities adopted for health interventions may impact our understanding, of whether inequalities are improving or worsening with time. Acknowledging social causation as an explanation for health inequalities, several possible mechanisms have been explored to explain how social conditions affect health
