Accreditation is the independent, third-party evaluation of a conformity assessment body (such as certification body, inspection body or laboratory) against recognised standards, conveying formal demonstration of its impartiality and competence to carry out specific conformity assessment tasks (such as certification, inspection and testing).

Accreditation bodies are established in many economies with the primary purpose of ensuring that conformity assessment bodies are subject to oversight by an authoritative body. Accreditation bodies, that have been peer evaluated as competent, sign regional and international arrangements to demonstrate their competence. These accreditation bodies then assess and accredit conformity assessment bodies to the relevant standards.

An authoritative body that performs accreditation is called an 'accreditation body'. The International Accreditation Forum (IAF) and International Laboratory Accreditation Cooperation (ILAC) provide international recognitions to accreditation bodies. There are many internationally recognized accreditation bodies approved by the IAF and ILAC.

The Emirates International Accreditation Centre (EIAC) is the largest accreditation body in Middle East region, whereas in South Asia the Pakistan National Accreditation Council (PNAC) and National Accreditation Board for Testing and Calibration Laboratories (NABL), Quality Council of India (QCI) are the largest. In East Asia, the China National Accreditation Board is the largest, while the United Kingdom Accreditation Service (UKAS) is the largest in Europe. The National Association of Testing Authorities (NATA) and the Joint Accreditation System of Australia and New Zealand (JAS-ANZ) being the largest in the Oceania region, with the South African National Accreditation System being the largest in Africa.

For most of the accreditation schemes, international standards issued by the International Organization for Standardization (ISO) are used.