PRINCE2 is part of a family of standards called best practices that are owned by AXELOS. AXELOS is a UK-based joint venture that took this responsibility, replacing the previous owner, OGC.
OGC and AXELOS have always used third-party examination institutes for the exam. These organizations are responsible for accrediting training organizations and trainers, preparing basic material, conducting the PRINCE2 exams , and issuing certificates. Exam questions are designed by AXELOS instead of the examination institute(s).
Multiple institutes have been responsible for the best practice exams. A while after initiating the exams, it was exclusively done by APMG, and some people even think that PRINCE2 and ITIL belong to APMG. Then, AXELOS started working with multiple examination institutes, and at a certain time, exams were delivered by APMG, EXIN (which has a long history of delivering these exams), PeopleCert, and a few smaller organizations. Recently, AXELOS decided to work with only one examination institute, and their selected one was PeopleCert. So, at the moment, the only examination institute for PRINCE2 and other best practice exams is PeopleCert.
Training organizations can apply and become accredited to deliver classroom and eLearning courses and exams. Then, they can take paper-based exams at the end of their classroom courses or sell vouchers for the online official exam.