Certification refers to the confirmation of certain characteristics of an object, person, or organization. This confirmation is often, but not always, provided by some form of external review, education, assessment, or audit. Accreditation is a specific organization's process of certification.
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, in Russia it is the GOST R Rostest.
In first-party certification, an individual or organization providing the good or service offers assurance that it meets certain claims. In second-party certification, an association to which the individual or organization belongs provides the assurance. Third-party certification involves an independent assessment declaring that specified requirements pertaining to a product, person, process or management system have been met. In this respect, a Notified Body is a third-party, accredited body which is entitled by an Accreditation Body. Upon definition of standards and regulations, the Accreditation Body may allow a Notified Body to provide third-party certification and testing services. All this in order to ensure and assess compliance to the previously defined codes, but also to provide an official certification mark or a declaration of conformity. 
Certification in software testing
For software testing the certifications can be grouped into exam-based and education-based. Exam-based certifications: For this there is the need to pass an exam, which can also be learned by self-study: e.g. for International Software Testing Qualifications Board Certified Tester by the International Software Testing Qualifications Board  or Certified Software Tester by QAI or Certified Software Quality Engineer by American Society for Quality. Education-based certifications are the instructor-led sessions, where each course has to be passed, e.g. Certified Software Test Professional or Certified Software Test Professional by International Institute for Software Testing.  
Types of certification
- Academic degree
- Professional certification
- Product certification and certification marks
- Cyber security certification
- Digital signatures in public-key cryptography
- Music recording sales certification, such as "Gold" or "Platinum"
- Film certification, also known as Motion picture rating system 
- Professional certification (computer technology)
- Diving certification
- Laboratory Certification and audits 
- Environmental certification
- Dovetail Partners
- Boiler and Pressure Vessel Inspection According to ASME
- NABL Certified Lab
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- "Academic Degrees Abbreviations". Abbreviations.com. Retrieved 2014-01-30.
- "Certifications". Caslab.com. Retrieved 2014-01-30.
- Institute for Credentialing Excellence What is Certification?[dead link] Nov 23, 2018
- International Certification Accreditation Council (ICAC)
- Forest Certification Center (Metafore)
- American National Standards Institute
- International Organization for Standardization
- Programme for the Endorsement of Forest Certification (PEFC)