'Public health' refers to the science and practice of protecting and improving the health of populations—rather than individuals—through prevention, education, policy, and environmental interventions. The term combines four characters: 公 (gōng, 'public' or 'common'), 共 (gòng, 'shared' or 'joint'), 卫 (wèi, 'to guard' or 'to defend'), and 生 (shēng, 'life' or 'health'). Together, they literally mean 'guarding shared life,' reflecting its collective, preventive nature.

This word is widely used in official, academic, and media contexts—such as public health campaigns, disease surveillance, vaccination programs, and sanitation policy. It appears frequently in government reports, news about epidemics, and health education materials. Unlike 个人卫生 (personal hygiene), which focuses on individual habits, 公共卫生 emphasizes community-level systems like clean water supply, food safety regulation, and infectious disease control.