Although this type of testing has been done for a long time there is still usually some confusion about what is involved. There are many types of testing including testing for performance, robustness, behavior, functions and interoperability. Conformance testing may include some of these kinds of tests but it has one fundamental difference. Conformance testing is testing to see if an implementation meets the requirements of a standard or specification. The requirements or criteria for conformance must be specified in the standard or specification, usually in a conformance clause or conformance statement.
Some standards have subsequent standards for the test methodology and assertions to be tested.
If the criteria or requirements for conformance are not specified there can be no conformance testing. The general definition for conformance has changed over time and been refined for specific standards. In recent years, the term conformity has gained international use and has generally replaced the term conformance in ISO documents. Conformity assessment is meant to provide the users of conforming products some assurance or confidence that the product behaves as expected, performs functions in a known manner, or has an interface or format that is known. Conformity assessment is NOT a way to judge if one product is better than another.