A graduate certificate or diploma (the terms are used interchangeably in North America) in nursing denotes specialization in a sub-field or discipline of nursing gained through intensive graduate-level study. As such, it supplements an already established area of expertise (in nursing or not related to the field) and adds value to a previously earned Bachelor's or graduate degree. Delivered in various formats from residential to online, graduate certificates in nursing comprise 4 - 6 courses (typically 12 - 18 credit hours) taken in a prescribed sequence at the graduate level.
The concurrent graduate certificate or diploma in nursing allows students currently enrolled in a Master's or Doctoral degree program in the field to pursue an in-depth exploration of one aspect of their field. For example, a student working towards a Master's in Nursing with a specialization in Acute Care Nursing may take the Graduate Certificate in Nursing Administration to augment their expertise.
The stand-alone, direct-entry graduate certificate/diploma program in nursing provides an opportunity for graduate-level study of theory and research to students who are not interested in pursuing a full graduate degree. This could include professionals with a Bachelor's degree working in the field or anyone who does not have the time or interest in a traditional graduate program in nursing. Then too, some students who take the stand-alone certificate already have a graduate degree and use their certificate to augment a particular area of interest.
A selection, but not inclusive list, of graduate certificates/diplomas in nursing includes

Graduate Certificate - Acute Care Nurse Practitioner

Graduate Certificate - Acute Care Pediatric Nurse Practitioner

Graduate Certificate - Adult Nurse Practitioner

Graduate Certificate - Family Nurse Practitioner

Graduate Certificate - Gerontological Nurse Practitioner

Graduate Certificate - Mental Health Nurse Practitioner

Graduate Certificate - Pediatric Nurse Practitioner

Graduate Certificate in Patient Safety, Error Science and Full Disclosure

Graduate Certificate in Hospice, Palliative Care and End of Life Studies

Graduate Certificate - Neonatal Nurse Practitioner

Graduate Certificate in Nursing Administration

Graduate Certificate in Nursing and Healthcare Informatics

Graduate Certificate in Nursing Education

Graduate Certificate in Occupational Health Nursing