नर्स या उपचारिका, एक पेशेवर स्वास्थ्य कर्मी है जो, स्वास्थ्य सेवा दल के अन्य सदस्यों के साथ किसी रोगी के उपचार और सुरक्षा, लंबे समय से (चिरकालिक) या गंभीर रूप से (अतिपाती) बीमार व्यक्तियों के स्वास्थ्य सुधार, परिवारों और समुदायों में विभिन्न स्वास्थ्य संबंधी सेवायों की जानकारी और उनका प्रयोग और किसी आपदा के समय प्रभावित लोगों को उपचार या स्वास्थ्य सेवायें प्रदान कराने के लिए उत्तरदायी है।

Nursing is a profession within the healthcare sector focused on the care of individuals, families, and communities so they may attain, maintain, or recover optimal health and quality of life. Nurses can be differentiated from other healthcare providers by their approach to patient care, training, and scope of practice. Nurses practice in many specialties with differing levels of prescription authority. Nurses comprise the largest component of most healthcare environments; but there is evidence of international shortages of qualified nurses. Nurses collaborate with other healthcare providers such as physicians, nurse practitioners, physical therapists, and psychologists. There is a distinction between nurses and nurse practitioners; in the U.S., the latter are nurses with a graduate degree in advanced practice nursing, and are permitted to prescribe medications unlike the former. They practice independently in a variety of settings in more than half of the United States. Since the postwar period, nurse education has undergone a process of diversification towards advanced and specialized credentials, and many of the traditional regulations and provider roles are changing.