What is Conformance Testing?

Conformance Testing 
In software testing, conformance testing is testing to determine whether a system meets some externally-specified standard. Compilers, for instance, are extensively tested to determine whether they meet the recognized standard for that language.
To aid in this, many test suites have been developed, either by the standard's maintainers or external organizations, specifically for testing conformance to standards. 

Conformance testing is often performed by external organizations, sometimes the standards body itself, to give greater guarantees of compliance. Products tested in such a manner are then advertised as being certified by that external organisation as complying with the standard.