Note: This article is on the medical profession of nursing. For the activities of a wet nurse, see Breastfeeding.

Nursing is a discipline focused on assisting individuals, families and communities in attaining, re-attaining and maintaining optimal health and functioning. Modern definitions of nursing define it as a science and an art that focuses on quality of life as defined by persons and families. Nursing is not only concerned about health and functioning but with quality of living and dying, lived experience, and universal lived experiences of health.

Like other maturing disciplines, nursing has developed different theories that are aligned with diverging philosophical beliefs and paradigms or worldviews. Nursing theories help nurses to direct their activities in order to accomplish specific goals with people. Nursing is a knowledge based discipline committed to the betterment of humankind.

A nurse practices nursing as a profession. There are a number of educational paths to becoming a professional nurse and in many countries, nursing practice is regulated by law. Advanced practice nurses include nurses with advanced education, generally at the graduate school level. Advanced practice nurses include nurse practitioners, clinical nurse specialists, certified nurse midwives and nurse anesthetists. There also are some nurse researchers who have PhDs in nursing or other fields and study human responses to health and illness in many settings. There are other nurses with PhDs who practice with persons who are changing their health patterns. Nurses help people figure out what they need to go on, what they see as possible, how they want to change, how they can move toward their hopes and dreams.

Nurses acknowledge that the nursing profession is an essential part of the society from which it has grown. The authority for the practice of nursing is based upon a social contract that delineates professional rights and responsibilities as well as mechanisms for public accountability. The American Nurses' Association (1980) has defined nursing as "the diagnosis and treatment of human responses to actual or potential health problems." Just as medical diagnoses help in the planning, implementing, and evaluation of medical care, Nursing diagnoses help in the planning, implementing, and evaluation of nursing care.

Nurses practice in a wide range of settings from hospital to visiting people in their homes. Nursing is the most diverse of all healthcare professions. It is a universal phenomenon appearing in some form in every culture.