A registered nurse is a nurse

Nursing

Nursing is a healthcare profession focused on the care of individuals, families, and communities so they may attain, maintain, or recover optimal health and quality of life from conception to death....

 who has graduated from a nursing program

Nursing school

A nursing school is a type of educational institution, or part thereof, providing education and training to become a fully qualified nurse. The nature of nursing education and nursing qualifications varies considerably across the world.-United Kingdom:...

 at a university or college and has passed a national licensing exam. A registered nurse helps individuals, families, and groups to achieve health and prevent disease. They care for the sick and injured in hospitals and other health care facilities, physicians' offices, private homes, public health agencies, schools, camps, and industry.