Conformity assessment mainly includes four types: testing, inspection, certification and accreditation. According to the definition in the international standard ISO/IEC17000 "Vocabulary and General Principles for Conformity Assessment", it is described as follows:

Testing is "an activity that determines one or more characteristics of the object of conformity assessment according to a procedure". In layman's terms, it is an activity that uses instruments and equipment to evaluate in accordance with technical standards and specifications, and the evaluation result is test data.

Inspection refers to "the activity of checking product design, product process or installation and determining whether it meets specific requirements, or determining whether it meets general requirements based on professional judgment". In layman's terms, it relies on people's experience and knowledge, and uses test data or other evaluation information to determine whether it complies with relevant regulations.

Metrology testing and certification is "a third-party certification related to products, processes, systems or personnel". In layman's terms, it refers to the conformity assessment activities of a certification body with a third-party nature to prove that products, services, management systems and personnel meet relevant standards and technical specifications.

Certification is "a third-party certificate that formally indicates that a conformity assessment body has the ability to carry out specific conformity assessment work". In layman's terms, it refers to the conformity assessment activities of a certification body to prove the technical capabilities of certification bodies, inspection bodies and laboratories.

According to the above definition, the objects of inspection, testing and certification are products, services and corporate organizations (directly facing the market), while the objects of recognition are institutions engaged in inspection, testing and certification (indirectly facing the market).