One of the most common types of certification in modern society is professional certification, where a person is certified as being able to competently complete a job or task, usually by the passing of an examination.
There are two general types of professional certification: some are valid for a lifetime, once the exam is passed. Others have to be recertified again after a certain period of time. Also, certifications can differ within a profession by the level or specific area of expertise they refer to. For example, in the IT Industry there are different certifications available for software tester, project manager, and developer. Similarly, the Joint Commission on Allied Health Personnel in Ophthalmology offers three certifications in the same profession, but with increasing complexity.
Certification does not refer to the state of legally being able to practice or work in a profession. That is licensure. Usually, licensure is administered by a governmental entity for public protection purposes and a professional association administers certification. Licensure and certification are similar in that they both require the demonstration of a certain level of knowledge or ability.
Another common type of certification in modern society is product certification. This refers to processes intended to determine if a product meets minimum standards, similar to quality assurance. Different certification systems exist in each country. For example, the in Russia it is the GOST R Rostest.