Certifications may be perpetual, may need to be renewed periodically, or may be valid for a specific period of time. Although it is more common in regard to licensure, sometimes as part or whole of the renewal of an individual's certification, the individual must show evidence of continual learning, often termed continuing education, or earning continuing education units.

Certifications are offered through a certification body. This is usually a business organization, and sometimes a professional body. Sometimes, the organization's business is directly related to the certification, as in a software firm that certifies individuals as competent to use its products. In other cases, an organization, often a not for profit organization exists wholly, or in large part, to offer a particular certification. Whatever its nature, the certifying body determines the policies of the certification program. Potential consumers of a certification wish to understand the nature of the certifying body and the certification process. An individual who bears a designation but appears unable to perform competently is said to be a paper tiger because their resume suggests that they are more effective than they actually are.

Recreational Scuba diving does not have a centralized certifying or regulatory agency, and is mostly self regulated. There are, however, several large diving organizations that train and certify divers and dive instructors, and many diving related sales and rental outlets require proof of diver certification from one of these organizations prior to selling or renting certain diving products or services. The Professional Association of Diving Instructors (PADI) is the world's largest recreational diving membership and diver training organization founded by John Cronin and Ralph Erikson.