The purpose of licensing, whether admitted or not, is to restrict entry and control a profession or activity. Certification is not a permission to act, but rather a statement of completion or qualification. Certification is a private matter, issued by a private organization. It does not involve the police power of the state, and is not a state privilege. Certification is based on the premise that there is a right to work.
Certification only provides the consumer with more information about a practitioner.
It also gives practitioners a way to increase their competency through a course of study and exams, and to advertise or inform others of their completion of this course of study. The purpose of certification is mainly to set standards, educate practitioners and inform the public. It may, however, be used to control entry if combined with state laws. See the section below on 'combinations'. Dietitians, for example, are registered in most states.